ABSTRACT
BACKGROUND: The significance of socioeconomic status (SES) in child mental health is well-established in Western populations; however, there is little evidence on this topic in Chinese populations. The possibility that Chinese families with different SES elicit different parenting practices that cause positive or negative child mental health outcomes warrants further investigation. METHODS: This study examined the associations of SES, parenting practices, and child mental health among 1401 Chinese school children and their parents residing in Shanghai. SES was measured by a composed index of parental education levels, occupations, and household incomes. The Alabama parenting questionnaire (APQ; child version) and the strengths and difficulties questionnaire (SDQ; parent version) were used to assess parenting practices and child mental health. We also explored the underlying mechanisms between parental SES and the mental health of children by testing different parenting practices as mediators of the relationships. RESULTS: The results showed that a higher SES is positively associated with better mental health in children. Positive involvement and deficient monitoring can mediate the relationship between SES and child mental health outcomes. Negative discipline did not significantly mediate the above relationship. CONCLUSIONS: The results highlight the significance of positive involvement and sufficient monitoring in promoting children's mental health and provide evidence for designing effective programs to improve parenting skills.
ABSTRACT
To improve the tensile strength and wear resistance of AlSi10Mg alloys, a novel in situ synthesis method of selective laser melting (SLM) was used to fabricate the Ni-reinforced AlSi10Mg samples. The eutectic Si networks formed around the α-Al crystals by diffusion and transportation via Marangoni convection in the SLM process. Moreover, the XRD and TEM results verified that the Al3Ni nanoparticles were created by the in situ reaction of the Ni and aluminum matrix in the Ni/AlSi10Mg samples. Therefore, the microstructure of the Ni-containing alloys was constituted by the α-Al + Si network + Al3Ni phases. The dislocations accumulated at the continuous Si network boundaries and cannot transmit across the dislocation walls inside the Si network. SEM results revealed that the continuity and size of eutectic Si networks can be tailored by adjusting the Ni contents. Furthermore, the Al matrix also benefited from the Al3Ni nanoparticles against the dislocation movement due to their excellent interfacial bonding. The 3Ni-AlSi10Mg sample exhibited high mechanical properties due to the continuous Si networks and Al3Ni nanoparticles. The tensile strength, elongation, Vickers hardness, friction coefficient, and wear volumes of the 3Ni-AlSi10Mg samples were 401.15 ± 7.97 MPa, 6.23 ± 0.252%, 144.06 ± 0.81 HV, 0.608, 0.11 mm3, respectively, which outperformed the pure AlSi10Mg samples (372.05 ± 1.64 MPa, 5.84 ± 0.269%, 123.22 ± 1.18 HV, 0.66, and 0.135 mm3).
