The surface topography of cracks in strained In0.72Ga0.28P films

Cracks in a 2% tensile strained In_0.72Ga_0.28P film grown on an InP substrate by molecular-beam epitaxy have been studied by cross-section transmission electron microscopy and scanning probe microscopy. A dislocation analogue (i.e. replacing the crack by an array of equivalent infinitesimal edge dislocations) is employed to account for the ratio of the crack-opening displacement to the normal surface displacement associated with the crack.     

Effect of sample size on ductility of metallic glass

With decreasing sample dimension, the compressive plastic strain of a Zr-based metallic glass increases from near zero to as high as 80% without failure. This indicates that macroscopically brittle or ductile deformation behaviour can occur in chemically and structurally identical metallic glass. A concept of critical shear offset is proposed to explain the strong size effect on the enhanced plasticity of metallic glass by taking the shear fracture energy density into account. This finding provides new understanding on the principle that for metallic glass ‘smaller is more ductile’, even on the macroscopic scale.     

Enhanced plastic deformation in a metallic glass induced by notches

It is shown that the compressive plasticity of a metallic glass, namely Zr_52.5Ni_14.6Al₁₀Cu_17.9Ti₅, can be improved by the introduction of two symmetrical notches. The enhanced plasticity may be ascribed to a blocking effect of the propagation of shear bands caused by large stress gradients around the notches. In contrast to ceramic specimens with similar notches, the plasticity enhancement of metallic glass induced by notches can provide a new approach to understanding its unique mechanism of deformation.     

Microstructure dependence of nanometre corrosion in Al-Ni-Y glassy alloys

The study reports the discovery of a new structure and spacing versus angle relation for a prevalent type of small-angle grain boundary in YBa     

Importance of chamber gas pressure on processing of Al-based metallic glasses during melt spinning

The effect of chamber gas pressure on the amorphicity of Al₈₅Ni₅Y₁₀ alloy was studied for the melt-spinning process. The amorphicity of as-quenched ribbons was characterized by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The chamber atmosphere pressure is crucial to the cooling rate of melt spinning. At high vacuum, at pressure less than 0.001?atm, fully crystalline fragments are obtained. Monolithic amorphous ribbons were only obtained at a gas pressure of 0.1?atm, 0.2?atm or higher. The extended contact length between ribbons and the copper wheel contributes to the high cooling rate of melt spinning in Al-based glass forming alloys; that is supported by images recorded by a high-speed camera. Higher chamber pressure increases contact length between ribbons and the wheel, which is qualitatively elucidated by Bernoulli's equation.     

Amorphization of cubic zirconia by caesium-ion implantation

Stabilized cubic zirconia is a promising candidate material for use as an inert fuel matrix for 'burning' excess Pu in light-water nuclear reactors. Zirconia is also considered to be an excellent nuclear waste form for direct geological disposal. Both applications are based on zirconia's high solubility for actinides, high chemical durability and high stability under irradiation. We report the first evidence of solid-state amorphization of yttria-stabilized cubic zirconia (YSZ) by 400keV Cs-ion implantation to 1 x 10²¹ ions m^-2 at room temperature. Amorphization of YSZ is caused by the large size incompatibility and low mobility of Cs ions in the YSZ structure, reflecting a relatively low solubility of Cs in YSZ. Nevertheless, the Cs concentration at which amorphization of YSZ occurred (about 8at.%) is well above the value that will typically be reached in an inert fuel matrix.     

The alpha -> beta polytypic transformation in SiC induced by ball milling

The alpha -> beta polytypic transformation in SiC was observed during ball milling at room temperature. Microstructural evolution was characterized on an atomic scale by high-resolution electron microscopy (HREM). HREM observations showed that partial dislocations play an important role in the transformation under the complicated conditions during ball milling.     

Self-efficacy Manipulation and State Anxiety Responses to Exercise in Low Active Women

The present study manipulated self-efficacy in an exercise context and examined its effect on the state anxiety of low active women. Participants ( N = 59) were randomly assigned to a low or high efficacy condition, and self-efficacy was manipulated by presentation of computer-generated false feedback after a graded exercise test. Participants returned for a second exercise bout several days later. Efficacy was successfully manipulated and participants in the high efficacy condition reported significantly less anxiety than those in the low efficacy condition both after the graded exercise test and before and after an acute bout of exercise. Results are discussed in terms of the effect of exercise intensity and manipulation condition on anxiety.     

Editorial

This study examined the psychometric properties of the Outcome Questionnaire-30.2 (OQ-30.2; designed to measure patient progress throughout mental health treatment) in a sample of United States Air Force active duty basic military trainees who were evaluated for mental health concerns during the course of basic training. Findings indicate that the OQ-30.2 was internally consistent and Total scores decreased with more contact with mental health professionals. Previously reported 1- and 3-factor structures were not replicated; rather, results suggested the use of a broad 27-item general psychological distress subscale and a separate subscale of 3 critical items assessing substance use concerns. Present findings support the utility of the OQ-30.2 as a tool for repeated monitoring of patient progress in military mental health settings. Recommendations for future directions in the development of alternate calculations of the clinical cut score and reliable change index are discussed.