The endless search for better alloys Hu, Qing-Miao; Yang, Rui
Science (American Association for the Advancement of Science),
10/2022, Letnik:
378, Številka:
6615
Journal Article
Recenzirano
Machine learning narrows down the enormous search space for functional materials
Researchers and engineers are constantly searching for materials with specific properties to drive the rapid ...development of various technologies. Because of the practically infinite combinations of materials, these searches need to be strategized. In the case of conventional alloys, they generally consist of a single principal metal element accompanied by other elements. More recently, researchers have ventured into looking for alloys with multiple principal elements (
1
,
2
). This type of alloy, called a high-entropy alloy (HEA), greatly expands the search space of alloys for materials design. On page 78 of this issue, Rao
et al.
(
3
) present a physics-informed machine-learning approach to screen alloys with low thermal expansion coefficient within the huge iron-cobalt-nickel-chromium (Fe–Co–Ni–Cr) and iron-cobalt-nickel-chromium-copper (Fe–Co–Ni–Cr–Cu) composition space. These materials, which expand and contract very little with temperature changes, make them valuable for application on precision instruments for which high dimensional stability of the components is required.
This study aims to investigate the effect of ethical leadership on employee attitudes (affective commitment and job satisfaction) and to examine the role of psychological empowerment as a potential ...mediator of these relationships. In total, 467 employees in Chinese public sector completed surveys across three separate waves. Confirmatory factor analysis and structural equation modeling were used to test hypotheses. The paper found a positive relationship between ethical leadership and both employee attitudes and further reveals that psychological empowerment fully mediates the relationship between ethical leadership and affective commitment while partially mediates the relationship between ethical leadership and job satisfaction. Testing of above relationships via a mediated approach is novel and contributes to the research on ethical leadership.
This study aimed to explore the relationships among ethical leadership (EL), affective commitment (AC), work engagement (WE), and employees’ creativity (EC). In total, 233 Chinese public sector ...employees completed the survey in three phases. We used confirmatory factor analysis (CFA) and structural equation modeling (SEM) to analyze the data. The paper found positive relationships between EL and WE and with EL and EC. The results further revealed that AC partially mediates the EL-WE relationship, while both AC and WE fully mediate the relationship between EL and EC. Testing these relationships via a multiple-mediated approach significantly contributed to the existing research on leadership.
The substitutional solute atom induced local lattice distortion (LLD) in dilute metal solid solution was believed to be uniform because the solute atom was supposed to occupy the high symmetry ...lattice site without breaking the point group symmetry of the crystal lattice. Contrary to this conventional picture, we report in this paper that substitutional Mo atom in Ti-Mo solid solution occupies an off-center position instead of the high symmetry lattice site and leads to highly non-uniform LLD, as evidenced by our first principles calculations. The physics underlying the off-center occupation and non-uniform LLD are shown to be the Jahn-Teller splitting of the degenerated d states of Mo atom. With which, the solid-solutions suffering from non-uniform LLD are predicted. The non-uniform LLD challenges the application of classical solid solution hardening model based on uniform LLD and spherical stress tensor assumption to this kind of solid solutions. This work also questions the traditional view that elementary substitutional solute atoms in metal solid solutions should not induce anelastic relaxation and internal friction.
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This paper analyzes the nonlocal elliptic system involving the p(x)-biharmonic operator. We give the corresponding variational structure of the problem, and then by means of Ricceri’s Variational ...theorem and the definition of general Lebesgue-Sobolev space, we obtain sufficient conditions for the infinite solutions to this problem.
Perineuronal nets (PNNs) are extracellular matrix structures consisting of chondroitin sulfate proteoglycans (CSPGs), hyaluronan, link proteins and tenascin-R (Tn-R). They enwrap a subset of ...GABAergic inhibitory interneurons in the cerebral cortex and restrict experience-dependent cortical plasticity. While the expression profile of PNN components has been widely studied in many areas of the central nervous system of various animal species, it remains unclear how these components are expressed during the postnatal development of mouse primary visual cortex (V1). In the present study, we characterized the developmental time course of the formation of PNNs in the mouse primary visual cortex, using the specific antibodies against the two PNN component proteins aggrecan and tenascin-R, or the lectin Wisteria floribunda agglutinin (WFA) that directly binds to glycosaminoglycan chains of chondroitin sulfate proteoglycans (CSPGs). We found that the fluorescence staining signals of both the WFA staining and the antibody against aggrecan rapidly increased in cortical neurons across layers 2–6 during postnatal days (PD) 10–28 and reached a plateau around PD42, suggesting a full construction of PNNs by the end of the critical period. Co-staining with antibodies to Ca2+ binding protein parvalbumin (PV) demonstrated that the majority of PNN-surrounding cortical neurons are immunoreactive to PV. Similar expression profile of another PNN component tenascin-R was observed in the development of V1. Dark rearing of mice from birth significantly reduced the density of PNN-surrounding neurons. In addition, the expression of two recently identified CSPG receptors — Nogo receptor (NgR) and leukocyte common antigen-related phosphatase (LAR), showed significant increases from PD14 to PD70 in layer 2–6 of cortical PV-positive interneurons in normal reared mice, but decreased significantly in dark-reared ones. Taken together, these results suggest that PNNs form preferentially in cortical PV-positive interneurons in an experience-dependent manner, and reach full maturation around the end of the critical period of V1 development.
•The development of PNNs in mouse V1 was examined using histochemical staining with WFA and anti-aggrecan antibodies.•The density of PNN-enveloped neurons rapidly increases during PD10-28 and reaches a plateau around PD42.•PNNs preferentially envelope parvalbumin-immunopositive interneurons.•The maturation of PNNs is dependent on visual experience and correlates well with the progress of the critical period of V1.•Two CSPG receptors – NgR and LAR – show a similar developmental expression profile with that of PNNs.
The severe local lattice distortion, induced mainly by the large atomic size mismatch of the alloy components, is one of the four core effects responsible for the unprecedented mechanical behaviors ...of high-entropy alloys (HEAs). In this work, we propose a supercell model, in which every lattice site has similar local atomic environment, to describe the random distributions of the atomic species in HEAs. Using these supercells in combination with ab initio calculations, we investigate the local lattice distortion of refractory HEAs with body-centered-cubic structure and 3d HEAs with face-centered-cubic structure. Our results demonstrate that the local lattice distortion of the refractory HEAs is much more significant than that of the 3d HEAs. We show that the atomic size mismatch evaluated with the empirical atomic radii is not accurate enough to describe the local lattice distortion. Both the lattice distortion energy and the mixing entropy contribute significantly to the thermodynamic stability of HEAs. However the local lattice distortion has negligible effect on the equilibrium lattice parameter and bulk modulus.
Drawing on social exchange theory, the present study seeks to understand how ethical leaders channel followers' responses to positive treatment from the organization into a dutiful mindset, resulting ...in in-role and extra-role performance. Specifically, it examines the influence of perceived organizational support on both followers' job performance and organizational citizenship behaviors, and the mediating effects of duty orientation on such relationships. In addition, it examines whether the mediated effects are contingent on the ethical leadership exhibited by the team leader. Based on multi-source, multi-level data obtained from 233 employees in 60 teams from the Chinese public sector, we found that ethical leadership moderated the mediated relationship between perceived organizational support and follower work behaviors through duty orientation, such that this relationship was stronger in the presence of higher ethical leadership.
This study examines the mediating effects of cognitive and affective trust on the relationship between follower perceptions of transformational leadership behavior and their work outcomes. Using data ...obtained from 318 supervisor–subordinate dyads from a manufacturing organization located in mainland China, structural equation modeling results revealed that affective trust fully mediated the relationships between transformational leadership and the work outcomes of followers, including their affective organizational commitment, organizational citizenship behaviors (OCBs), and job performance. In contrast, cognitive trust negatively mediated the relationship between transformational leadership and follower job performance, and had insignificant effects on their affective organizational commitment and organizational citizenship behaviors. These findings highlight the importance of affective trust as a mechanism which translates transformational leadership into positive work outcomes for the organization.
An outbreak of the 2019 novel coronavirus (COVID-19) has been ongoing in China since January 2020. The threat of infection affects the work and life of most of the population and may also damage ...sleep. This study aims to examine the subjective sleep status and mental health of the population during the peak of the COVID-19 epidemic.
The data were collected through an online questionnaire with a sample of 5461 individuals in China from February 5, 2020, to February 23, 2020. Participants were divided into four groups based on their degree of threat from COVID-19: Group 1 was most closely associated with COVID-19, including inpatients diagnosed with COVID-19, first-line hospital workers and first-line management staff; Group 2 included outpatients diagnosed with COVID-19 and patients who developed a fever and visited the hospital; Group 3 included people related to Group 1 or 2, such as their colleagues, relatives, friends and rescuers; and Group 4 was the farthest removed from contact with COVID-19, covering the general public affected by COVID-19 prevention strategies. The Insomnia Severity Index (ISI), Patient Health Questionnaire (PHQ-9), Generalized Anxiety Disorder Scale (GAD-7) and Acute Stress Disorder Scale (ASDS) were used.
Threat degree of COVID-19 (groups) had significant correlations with insomnia, depression, anxiety, and stress (p < 0.05, p < 0.01). Age, gender, and area (Hubei province or other provinces) had significant correlations with insomnia (p < 0.01). A total of 1380 (24.46%) participants were suspected of having major depression based on the PHQ-9. Additionally, 1042 (18.47%) participants were suspected of having generalized anxiety disorder based on the GAD-7. A total of 892 (15.8%) of the participants had Acute Stress Disorder (ASD) according to the ASDS. The prevalence of clinical insomnia during the outbreak was 20.05% (1131) according to the ISI. The factors of satisfaction with the current sleep pattern and how perceptible the symptoms of the current sleep pattern are to other people (p < 0.05) and the middle (difficulty staying asleep) and terminal (waking up too early) (p < 0.01) factors of the ISI were significantly different across groups. A total of 1129 (20.01%) participants spent more than one hour awake in bed.
The results indicated that insomnia is more severe in people who are female, young, living in the epicenter and experiencing a high degree of threat from COVID-19. As prevention and treatment efforts continue with regard to COVID-19, the general public has developed poor sleep hygiene habits, which deserve attention.
•It reported the immediate impact of sleep status of a large sample at the peak of the COVID-19 spread in China.•Reports on sleep habits of individuals in China by different degrees of COVID-19 threat.•The threat degree of COVID-19 is associated with the prevalence of anxiety, depression and acute stress disorder.•The general public has developed poor sleep hygiene habits which deserve attention.
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