Deformation twinning-mediated pseudoelasticity in metal–graphene nanolayered membrane

In this study, we investigated the deformation behaviour of metal–graphene nanolayered composites for five face-centred cubic metals under compression using molecular dynamics simulations. It was found that by increasing the thickness of the individual metal layers, the composite strength increased, while the deformation mechanism changed from buckling to deformation twining in Cu, Au and Ag, which was absent in the monolithic form of those metals of the same orientation and size. The deformation twinning was found to be enabled by the graphene layer, which introduced pseudoelasticity and shape memory effects in the nanolayered membrane with more than 15% recoverable compressive strain.     

Investigation of tensile deformation mechanisms at room temperature in a new Ni-based single crystal superalloy

The deformation microstructures of a new Ni-based single crystal superalloy, M 4706, have been characterized by transmission electron microscopy after interrupted tensile tests at room temperature. It is found that besides shearing of γ′ precipitates by strongly coupled dislocations, another unusual shearing process involving a single a/2 〈1?0?1〉 matrix dislocation as well as the formation of the isolated superlattice stacking fault and Shockley loop also operates actively during initial yielding. Based on experimental observations, occurrence of these different shearing processes is discussed.     

The Structure and Sources of Right‐wing Authoritarianism and Social Dominance Orientation

Right‐wing authoritarianism (RWA) and social dominance orientation (SDO) are widely used constructs in research on social and political attitudes. This study examined their hierarchical and correlative structure (across sexes, generations and rater perspectives), as well as how genetic and environmental factors may contribute to individual differences in them (using different rater perspectives and nuclear twin family data). We found a substantive common aspect (beyond shared artificial variance arising from socially desirable responding) underlying both RWA and SDO: aggression against subordinate groups. We discussed how this aspect could help to explain the commonly reported correlation between the two concepts in Western countries. Estimates of genetic and environmental components in RWA and SDO based on self‐reports were quite comparable with those based on peer reports. When controlling for error variance and taking assortative mating into account, individual differences in RWA were primarily due to genetic contributions including genotype–environment correlation, whereas variance in SDO was largely attributable to environmental sources shared and not shared by twins. The findings are discussed in terms of the utility of RWA and SDO as basic constructs to describe individual differences in social attitudes and with respect to the different patterns of genetic and environmental influences that underlie them. Copyright © 2016 European Association of Personality Psychology     

Additive and Synergetic Contributions of Neuroticism and Life Events to Depression and Anxiety in Women

In this genetically informative and longitudinal study of women, we investigated the nature of individual differences in tendencies to depression (TD) and anxiety (TA) as well as in the probability to develop unipolar mood disorders (UMDs), anxiety disorders (ADs) or both. Specifically, we examined the roles of neuroticism, negative and positive life events and their interplay as heritable and environmental factors of variance in TD and TA. Cross‐sectional data from a total of 1200 women including 232 patients (suffering from UMDs and/or ADs) and longitudinal data from 630 female twins including 260 complete pairs were analysed. The analyses yielded that variance in neuroticism mediated the vast majority of the genetic variance in both TD (about 85–90%) and TA (about 70–75%). Negative life events additionally contributed as risk factors accounting for common and specific environmental variance in both TD and TA, whereas positive life events only acted as protective factors in the case of TD. Moreover, TD but not TA was associated with both the probability of exposure and the sensitivity to negative life events and a negative life‐event balance (i.e. more negative than positive experiences). The results were discussed within the framework of additive, dynamic and synergetic diathesis–stress models. Copyright © 2016 European Association of Personality Psychology     

Is the association between childhood maltreatment and aggressive behavior mediated by hostile attribution bias in women? A discordant twin and sibling study

Understanding the mechanisms behind aggressive behavior (AGG) is vital so that effective prevention and intervention strategies can be developed. Maltreated children are hypothesized to be prone to social information processing biases, such as hostile attribution bias (HAB), which, in turn, may increase the likelihood of behaving aggressively. The first aim of the present study was to replicate findings regarding associations between childhood maltreatment (CM), HAB, and aggression in a population‐based sample of Finnish female twins and their sisters (N = 2,167). However, these associations might not be causal but instead confounded by familial factors, shared between the variables. The second aim was, thus, to test the associations when potential confounding by familial (genetic or common environmental) effects were controlled for using a multilevel discordant twin and sibling design within (a) 379 pairs of twins (n_pairs = 239) or siblings (n_pairs = 140), and (b) within the 131 monozygotic (MZ) twin pairs. Consistent with previous studies, HAB mediated the association between CM and AGG when familial confounding was uncontrolled. No support was found for the mediation when controlling for familial confounding. Between‐pair associations were found between CM and AGG, and between CM and HAB. In addition, within‐pair associations were found between HAB and AGG, and between CM and AGG, however, these were nonsignificant in the discordant MZ analysis, offering the most stringent control of familial confounding. The results indicate the necessity of taking familial confounding into account when investigating the development of AGG.     

Phase transformation of germanium by processing through high-pressure torsion: strain and temperature effects

Germanium has been processed by high-pressure torsion (HPT) under a nominal pressure of 24 GPa at room temperature and cryogenic temperature. The samples processed at room temperature were composed of a diamond-cubic Ge-I phase and a metastable tetragonal Ge-III phase. The formation of Ge-III was significantly suppressed and Ge-I and an amorphous phase, in addition to a small amount of body-centred-cubic Ge-IV, appeared in the case of cryogenic HPT processing at 100 K. The Ge-IV phase gradually disappeared at room temperature. These results indicated that shear strain and thermal energy are important for promoting the formation of Ge-III.     

Impact of coherent and incoherent twin boundaries on the microhardness of annealed nanocrystalline Ni–W alloys

The microstructural evolution of nanocrystalline Ni–W alloys with annealing temperature and more specifically grain boundary (GB) character is investigated through several techniques and correlated with the hardening behaviour. It is shown that two distinct regions can be identified in relation to the annealing temperature and the microstructural evolution. At temperatures below 550 °C (Regime I), a small increase in grain size is observed and is accompanied by a significant hardening and an increase in the fraction of Σ3 incoherent twin boundaries. At temperatures above 550 °C (Regime II), the thermal stability is overcome and important grain growth occurs with a decrease in both the volumic fraction of GBs and the microhardness. It is suggested that the microhardness evolution during heat treatment is influenced by two opposing processes: an increase in the fraction of incoherent twin boundaries (hardening effect) and grain growth (softening effect). Both aspects are directly associated with the mean free path of mobile dislocations.     

Double reorientation in 〈1 1 0〉 Cu nanowires

Molecular dynamics simulations performed on tensile deformation of 〈1?1?0〉 Cu nanowire indicated that the nanowire undergoes double reorientation from 〈1?1?0〉 to 〈1?0?0〉 tensile axis followed by 〈1?0?0〉 to 〈1?1?2〉 tensile axis. It has been observed that the double reorientation results from the occurrence of twinning mode of deformation in both the original 〈1?1?0〉 and reoriented 〈1?0?0〉 Cu nanowires. The double reorientation in 〈1?1?0〉 Cu nanowire leads to tensile ductility as high as 260% thereby displaying superplastic like behaviour. The occurrence of double reorientation and the associated high tensile ductility have been restricted to low nanowire length below or equal to 7.15 nm with aspect ratio ≤1. Above this length (higher aspect ratio), the reorientation process has not been observed and the nanowire fails at significantly lower strains due to activation of multiple twin systems facilitating twin–twin interactions.     

Home environmental influences on children's language and reading skills in a genetically sensitive design: Are socioeconomic status and home literacy environment environmental mediators and moderators?

This twin study examined how family socioeconomic status (SES) and home literacy environment (HLE) contributes to Chinese language and reading skills. It included 312 Chinese twin pairs aged 3 to 11. Children were individually administered tasks of Chinese word reading, receptive vocabulary and reading‐related cognitive skills, and nonverbal reasoning ability. Information on home environment was collected through parent‐reported questionnaires. Results showed that SES and HLE mediated shared environmental influences but did not moderate genetic influences on general language and reading abilities. Also, SES and HLE mediated shared environmental contributions to receptive vocabulary and syllable and rhyme awareness, but not orthographic skills. The findings of this study add to past twin studies that focused on alphabetic languages, suggesting that these links could be universal across languages. They also extend existing findings on SES and HLE's contributions to reading‐related cognitive skills.