儿童早期工具行为发展的研究

本研究考察了一岁半到五岁半儿童工具行为发展及其与言语发生和主客体分化的关系。结果表明:使用直接性工具能力的出现几乎与言语发生和主客体分化同步,使用间接性工具的能力则晚出得多,要到三岁至四岁。这意味着:(1)当代人学研究起点应当从“直接工具行为×言语发生×主客体分化”后移。(2)三岁半左右是儿童智力发展超出动物水平的转折期,也是导入间接性工具游戏和训练的最佳年龄。(3)“智力重演说”与“自智人或晚期直立人起人类才有口语”的推测是互相排除的。     

自控速度的平滑滚动引导式和RSVP的文本阅读

考察了在自控速度条件下 ,显示窗口、起始速度和文本显示方式等因素对视频显示终端 (videodisplayter minals,VDT)汉语文本阅读工效的影响。结果发现 :(1)在阅读正确率上 ,VDT文本的平滑滚动引导式优于快速系列视觉呈现 (rapidserialvisualpresentation ,RSVP)方式 ;(2 )阅读速度和阅读理解成绩相互代偿 ,若注重理解正确率 ,宜采用 15 0字 /分的起始速度 ;若兼顾阅读速度 ,宜采用 75 0字 /分的起始速度 ;(3)起始速度、显示窗口和文本显示方式三者共同影响了阅读绩效 ;(4 )机控速度方式的阅读效率优于自控速度方式。     

Can boundary crossings in clinical supervision be beneficial?

Published studies have addressed boundary violations by clinical supervisors, but boundary crossings, particularly those deemed positive by supervisees, have not received much attention. Eleven trainees in APA-accredited doctoral programs in clinical and counseling psychology were interviewed regarding positive boundary crossings (PBCs) they experienced with clinical supervisors. Interview data were analyzed using Consensual Qualitative Research. Examples of PBCs included socializing with supervisors outside the office, sharing car rides, and supervisor self-disclosure. Typically, supervisees did not discuss the PBC with their supervisors because they were uncomfortable doing so, felt that the PBC was normal, or felt that processing such issues was not part of the supervisor’s style. Most supervisees viewed the PBCs as enhancing the supervisory relationship and their clinical training; however, some participants reported that the PBCs created role confusion. The results suggest that there are legitimate reasons for supervisors to be scrupulous about their boundaries with supervisees; however, supervisors who hold rigid boundaries can deprive supervisees of deeper mentoring relationships or a more authentic emotional relationship that can be valuable to supervisees learning how to provide psychotherapy.     

Dynamic balance between grain refinement and grain growth during high-pressure torsion of Cu powders

High-pressure torsion (HPT) was applied to unmilled coarse-grained (CG) Cu powders with low initial dislocation density and cryomilled nanocrystalline (nc) Cu powders with high initial dislocation density, with identical processing parameters. HPT of unmilled CG Cu powders resulted in exceptional grain refinement and increase in dislocation density, whereas significant grain growth and decrease in dislocation density occurred during HPT of cryomilled nc Cu powders. Equilibrium structures were achieved under both conditions, with very similar stable grain sizes and dislocation densities, suggesting dynamic balances between deformation-induced grain refinement and grain growth, and between deformation-induced dislocation accumulation and dislocation annihilation. The equilibrium structures are governed by these two dynamic balances.     

Enhanced grain growth in yttria-doped zirconia thin film structures synthesized under photon irradiation

Enhanced grain growth in ultra-thin yttria-doped zirconia (YDZ) films synthesized under ultraviolet (UV) irradiation is reported. The mean grain size in UV-synthesized 7.5 mol% YDZ films nearly 56 nm thick increased to 85 nm upon annealing in an oxygen-rich ambient at 900°C for 1 h, while in thermally grown YDZ they grew only to ～15 nm under identical annealing conditions. In situ electron microscopy kinetic studies reveal an enhanced kinetic constant and self-limiting grain growth behaviour in the UV-synthesized oxide films. The difference between UV and thermally grown films was not significant in undoped films when compared to the case of 7.5 mol% YDZ.     

First-principles pseudopotential study of an aluminium grain boundary containing sulphur atoms

The electronic structure of an aluminium grain boundary with segregated sulphur impurity atoms has been calculated by a first-principles pseudo-potential method. It is found that a sulphur atom bonds to only one of the neighbouring aluminium atoms. This bond is a mixed-character metallic-covalent bond which is stronger than the metallic Al-Al bonds. Electrons that participate in forming this bond are 3p electrons of sulphur but not its 3s electrons. Other Al--S bonds in the boundary contain no covalent character. From the nature of Al--S bonds in the boundary it cannot be decided whether the embrittlement promotion mechanism by sulphur segregation should be classified as a 'bond mobility model' or a 'decohesion model'.     

Stress-enhanced grain growth in a nanostructured aluminium alloy during spark plasma sintering

In this study, we report on the influence of high pressure on the microstructure evolution of cryomilled nanostructured Al alloy powders during spark plasma sintering (SPS). Our experimental results suggest that the particular mechanism that governs grain growth during SPS depends on the magnitude of the applied pressure. In the case of material consolidated at a high pressure (e.g. 500 MPa), grain coarsening occurs via a combination of thermally activated grain boundary (GB) migration, stress-coupled GB migration and grain rotation-induced grain coalescence. In contrast, in the case of the material consolidated at a low pressure (50 MPa), grain growth occurs primarily via thermally activated GB migration.     

TEM study of defects generated in 4H-SiC by microindentations on the prismatic plane

The deformation microstructure of single crystals of 4H-SiC resulting from microindentations on a prismatic surface was investigated by TEM. Indentations were performed at 400 and 675°C, i.e. below the brittle to ductile transition temperature of 4H-SiC (temperature close to 1100°C). TEM analysis reveals dissociated dislocations as well as extended stacking faults in the basal plane. In addition, perfect edge dislocations are observed on prismatic planes. From the observations, it is assumed that perfect dislocations are nucleated in the prismatic plane and cross-slip on the basal one where they dissociate.     

Anisotropic grain growth kinetics in nanocrystalline nickel

ABSTRACT

Intriguing properties exhibited by nanocrystalline metals, including a high level of mechanical strength, arise from their nanometer-scale grain sizes. It is critical to determine the evolution of grain size of nanocrystalline materials at elevated temperature, as this process can drastically change the mechanical properties. In this work, a nanocrystalline Ni foil with grain size ～ 25?nm was annealed in situ in an X-ray diffractometer. X-ray diffraction peaks were analysed to determine the grain growth kinetics. The grain growth exponents obtained were ～ 2–4 depending upon the crystallographic direction, indicating the anisotropic nature of the grain growth kinetics.