School Connectedness and Problematic Internet Use in Adolescents: A Moderated Mediation Model of Deviant Peer Affiliation and Self-Control

Although a growing body of research documents the negative association between school connectedness and adolescent problematic Internet use (PIU), little is known about the mediating mechanism (i.e., how school connectedness relates to PIU?) and moderating mechanism (i.e., when the protection is most potent?) underlying this relation. The present study examined whether deviant peer affiliation mediated the relationship between school connectedness and PIU, and whether this mediating process was moderated by adolescent self-control. A total of 2,758 Chinese adolescents (46 % male; mean age?=?13.53 years, SD?=?1.06) from 10 middle schools completed anonymous questionnaires regarding school connectedness, deviant peer affiliation, self-control, and PIU. After controlling for gender, age, socioeconomic status, and parental attachment, it was found that the negative association between school connectedness and adolescent PIU was partially mediated by deviant peer affiliation. Moreover, this indirect link was stronger for adolescents with low self-control than for those with high self-control. These findings underscore the importance of integrating the social control theory and organism-environment interaction model to understand how and when school connectedness impacts adolescent PIU.     

When the West Meets the East: Cultural Clash and Its Impacts on Anomie in a Sample of Chinese Adolescents

ABSTRACT

Criminological studies conducted in China have highlighted the important role of Chinese culture and anomie theory in explaining crime patterns and delinquency among adolescents. None of the studies, however, have empirically tested the relationship between cultural attachment and anomie. The purpose of this study is to examine the influence of ethnic identity associated with cultural attachment on anomie in the Chinese social setting. Specifically, the effects of both attachment to conventional Chinese culture and attachment to Western popular culture (WPC) were examined; the interaction between the two may shed some important light on how culture and cultural conflict can lead to anomie among Chinese adolescents. The data analyzed were collected from a sample of more than 6,500 middle school students. Structural equation modeling was employed to test the hypothesized relationships. The study found that attachment to traditional Chinese cultural values, especially showing respect to conventional figures/values, reduces anomie among adolescents. In contrast, attraction to WPC and being socially labeled as a big fan of WPC elevate the levels of anomie reported by the students. Reflections on cultural conflict and relevant policy implications are provided in the “Discussions and conclusions” section.     

Microstructure and martensitic transformation behaviors of a Ti–Ni–Hf–Cu high-temperature shape memory alloy ribbon

The Ti₃₆Ni₄₁Hf₁₅Cu₈ melt-spun ribbon undergoes a B2 ? B19′ transformation upon cooling and heating. When the Ti₃₆Ni₄₁Hf₁₅Cu₈ melt-spun ribbon is annealed at 873 K for 1 h, the spherical (Ti, Hf)₂Ni particles with a diameter of 20–40 nm precipitate in the grain interior. The fine (Ti, Hf)₂Ni precipitates improve the stability of phase transformation temperatures and cause martensite domains, with (001) compound twins in three orientations dominant instead of (011) type I twins. {111}-, {113}- and (001)//{111}-type boundaries are observed among these martensite domains. When the (Ti,Hf)₂Ni precipitates coarsen, (011) type I twins become main martensite structures in the ribbon annealed at 973 K for 1 h.     

Fractal patterns in Au–Ta multilayer films upon ion beam mixing

Metallic glass has been formed in Au₅₀Ta₅₀ multilayer films upon 200?keV xenon ion mixing at an irradiation dose of 1?×?10¹⁵?Xe⁺/cm². Electron diffraction and high-resolution transmission electron microscopy analysis confirm that the metallic glass consists of two amorphous phases, evolved from Au and Ta lattices, respectively, and also reveal the formation of a fractal morphology with a fractal dimension of 1.73?±?0.05 in the dual-phase glass features. In similar Au₆₅Ta₃₅ multilayer films, a fractal pattern is also observed at a dose of 1?×?10¹⁵?Xe⁺/cm², while the pattern, with a fractal dimension of 1.74?±?0.05, is composed in this case of a crystalline Au-based solid solution and a Ta-based amorphous phase. Interestingly, the fractal dimensions of the two irradiation-induced fractal patterns match quite well with that expected on a cluster diffusion-limited aggregation model.     

Microstructure evolution of Al-15% Si alloy during hot rolling

ABSTRACT

A direct chill (DC) cast Al-15% Si alloy was processed by hot rolling with a single pass at a temperature of 520°C with a thickness reduction of 80%. Scanning electron microscopy (SEM), electron backscattering diffraction (EBSD) and transmission electron microscopy (TEM) were used to investigate the evolution of the sample’s microstructure. After hot rolling, silicon particles homogeneously distributed in the Al matrix with fine equiaxed grains of average size ～ 0.95?μm. High-angle boundaries (HABs) (about ～75.8% in percentage) dominate in the Al matrix structure. There is evidence for Si-particle-stimulated continuous dynamic recrystallization (CDRX) during hot rolling.     

Alloying effects on sulphur embrittlement of the γ-γ′ interface of nickel-based single-crystal superalloys

Fully first-principles calculations have been performed to investigate the alloying effect on the sulphur embrittlement of the n - n ' interface of nickel-based single-crystal superalloys. The shear and cohesive strengths of the inter-face are calculated in terms of Mayer bond orders (BOs), and the ratio R BO of shear strength over cohesive strength is analysed as a function of alloying element substitution. The interface characteristics are also studied using the electron charge-density distribution. It is found that the interplay between shear and cohesive strengths has a significant influence on the interfacial embrittlement. Using the phenomenological theory of fracture as well as the calculated ratio R BO, we propose a new mechanism responsible for relieving sulphur embrittlement of the n - n ' interface through alloying substitution.     

Shear horizontal surface waves in piezoelectric materials with surface stress

ABSTRACT

The propagation of shear horizontal (SH) surface waves in piezoelectric semi-infinite bodies is investigated theoretically. The surface stress exerting on the boundary is taken into account through surface piezoelectricity theory, and the velocity ranges and existence conditions of such surface waves for both electrically open and shorted cases are derived in detail. Analysis results show that the SH surface waves occurring with surface stress are dispersive in contrast to the classical situation, and the propagation characteristics strongly depend on the relative value of surface elasticity, surface piezoelectricity and surface density.     

Nanocrystallization induced by quasi-static fracture of metallic glasses at room temperature

Nanoparticles on the fracture surfaces of Co- and Fe-based metallic glasses during quasi-static compression at room temperature have been observed using a high-resolution scanning electron microscope. In terms of the differential scanning calorimeter, those nanoparticles were identified to be a result of nanocrystallization induced by the rapid fracture. Finally, the nanocrystallization behavior was evaluated by taking into account the super-high crack propagation rate and high elastic energy, which contributed to the local temperature rise up to the onset of crystallization, T _x.     

多阶段增长模型的方法比较

多阶段增长模型（Piecewise Growth Modeling,PGM）可以解决发展趋势中具有转折点的情形,并且相对其他复杂的曲线增长模型,解释更简单.已有的统计方法主要通过多层线性模型和潜变量增长模型对多阶段模型进行估计.通过模拟研究,用HLM6.0和Mplus6.0对上述两种模型分别进行估计,结果发现在参数估计的精度上,两种估计方法没有差异,只是在犯一类错误的概率上后者略小.进一步通过对错误模型的探讨发现,在样本量小（n=50）,斜率变化小（△b=0.2）时,用线性模型拟合数据而非PGM所犯错误概率较小,整体拟合更佳.但随着样本的增加和斜率变化的增加,错误模型的犯错概率明显增大.故在实际应用中,为了能更好拟合数据,研究者应根据数据本身的情况选择恰当的模型.     

Sensitivity of Fit Indices to Model Misspecification and Model Types

The search for cut-off criteria of fit indices for model fit evaluation (e.g., Hu &; Bentler, 1999 Hu, L. and Bentler, P. M. 1999. Cutoff criteria for fit indexes in covariance structure analysis: Conventional criteria versus new alternatives. Structural Equation Modeling., 6: 1–55. [Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]) assumes that these fit indices are sensitive to model misspecification, but not to different types of models. If fit indices were sensitive to different types of models that are misspecified to the same degree, it would be very difficult to establish cut-off criteria that would be generally useful. The issue about SEM fit indices being sensitive to different types of models has not received sufficient attention, although there is some research suggesting that this might be the case (e.g., Kenny &; McCoach, 2003 Kenny, D. A. and McCoach, D. B. 2003. Effect of the number of variables on measures of fit in structural equation modeling. Structural Equation Modeling., 10: 333–351. [Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]). This study examines if fit indices are sensitive to different types of models while controlling for the severity of model misspecification. The findings show that most fit indices, including some very popular ones (e.g., RMSEA), may be sensitive to different types of models that have the same degree of specification error. The findings suggest that, for most fit indices, it would be difficult to establish cut-off criteria that would be generally useful in SEM applications.