In situ characterization of the martensitic transformation temperature of NiTi shape memory alloys via instrumented microindentation

A novel, instrumented microindentation technique was successfully used to measure the temperature associated with the martensitic transformation leading to the recovery of plastic strain in a Nickel–Titanium (NiTi) shape memory alloy. Following a standard indentation cycle, the indenter was partially unloaded such that a good contact was maintained between indenter and specimen surface. The onset and finish temperature of the martensitic transformation, the associated volume contraction, and the amount of the recovered plastic deformation were determined by quantifying the indenter displacement as a function of temperature. These experiments were compared to conventional measurements of the transformation temperature by differential scanning calorimetry and compression testing.     

Anisotropic thermal properties of single-wall-carbon- nanotube-reinforced nanoceramics

Dense single-wall-carbon-nanotube-(SWCNT)-reinforced alumina nanocomposites have been fabricated by a novel spark-plasma-sintering technique. Anisotropic thermal properties have been found in carbon nanotube composites. The introduction of ropes of SWCNTs gives rise to a decrease in the transverse thermal diffusivity with increasing carbon nanotube content while it does not change the in-plane thermal diffusivity. This is scientifically interesting and technologically important for the development of materials for novel thermal barrier coatings.     

Vertex interactions and film shapes in two-dimensional foam

A model of the structure of two-dimensional foam (cells separated by circular arcs (films) meeting at threefold vertices) is considered. Films that are so curved as to be nearly semicircular arcs are problematic for conventional foam structure computations, which aim to identify the pressures needed to achieve specified bubble areas. When the films have near semicircularity, tiny variations in pressure can lead to large changes in the computed bubble area, and hence a failure to meet the specified targets. A new algorithm for determining foam structure is presented. It is based on 'freezing' most of the system, except the nearly semicircular arcs, and then finding the particular bubble pressures associated with the latter via an analytic approximation. This procedure is shown to work well for structure relaxation in a small bubble cluster. Large relaxed bubble clusters are considered briefly at the end of the paper.     

Investigation of {111} stacking faults and nanotwins in epitaxial BaTiO3 thin films by high-resolution transmission electron microscopy

{111} stacking faults and nanotwins in epitaxial BaTiO₃ thin films on MgO substrates have been investigated by high-resolution transmission electron microscopy. In many cases, the stacking faults and nanotwins were found to be accompanied by partial dislocations. These partial dislocations can be classified as two different types, analogous to the situation in the fcc structure. One is of the Shockley type with the Burgers vector (a/3)<112>. The other is of the Frank type with the Burgers vector (a/3)<111>. The movements of both types of partial can lead to the {111} stacking faults and the {111} twins observed in these films.     

Thermodynamics of void nucleation in nanoparticles

The nucleation of voids at the initial stage of hollow nanoshell formation is described in terms of the thermodynamics of nucleation in systems of finite size (or small systems) pumped with vacancies by interdiffusion-driven vacancy influx. Crossovers from suppressed nucleation to metastable nucleus formation and then to stable nucleus formation are analysed, describing, in particular, the possibility of significant supersaturations with vacancies of the metallic core. It is shown that at higher temperatures it becomes more favourable to nucleate at once a large single void instead of multiple tiny voids.     

Molecular dynamics simulations of the size effect of titanium single-crystal nanopillars orientated for double prismatic slips

An inverse “smaller is stronger” trend is predicted on the basis of molecular dynamics simulations of α-titanium (Ti) single-crystal nanopillars orientated for double prismatic slips when the nanopillars are less than 7?nm wide. This trend is attributed to a significant increase in the surface energy due to the nucleation and propagation of edge dislocations on the surface of the pillars.     

In the Netherlands the anti-Flynn effect is a Jensen effect

In this study, 63 observations of secular IQ changes (both Flynn and anti-Flynn effects) are collected from three demographically diverse studies of the Dutch population for the period 1975–2005 (representing the 1950–1990 birth cohorts), along with data on g loadings and subtest reliabilities. The method of correlated vectors is used to explore the association between Flynn and anti-Flynn effect magnitudes, both independently and together, and the g loadings of subtests. Despite a positive vector correlation the Flynn effects are not associated with the Jensen effect (r = .307, ns, N = 36), however the anti-Flynn effects are (r = .406, P = .05, N = 27). Combined, the vector correlation becomes negative but non-significant (r = −.111, ns, N = 63). Declines due to the anti-Flynn effect are estimated at −4.515 points per decade, whereas gains due to the Flynn effect are estimated at 2.175 points per decade. The N-weighted net of these is a loss of −1.350 points per decade, suggesting an overall tendency towards decreasing IQ in the Netherlands with respect to these cohorts. The Jensen effect on the anti-Flynn effect suggests that it may be related to bio-demographic changes within the Netherlands which have reduced ‘genetic-g’, despite the presence of large, parallel gains on subtests that may be relatively more sensitive to cultural-environmental improvements.     

Establishing an association between the Flynn effect and ability differentiation

The relationship between the Flynn effect and ability differentiation is investigated in a reanalysis of published data on Estonian student cohorts tested in 1933/36, 1997/98 and 2006 on the National Intelligence Test (Must, te Nijenhuis, Must, & van Vianen, 2009). To determine whether there was a relationship we computed the vector correlation between the Flynn effects (d) and the change in the g loading (Δg) between measurement occasions for each of the 10 NIT subtests and for each of the seven cohort comparisons, giving a total N of 70 effect sizes. The association between d and Δg was robustly negative (indicating that the Flynn effects were negatively associated with changes in the g loading of subtests) for all cohort comparisons, with values of r ranging from −.100 to −.461 (N = 10). When all effect sizes were analyzed together, the vector correlation was found to be −.281 (p ? .05, N = 70). This indicates a significant association between the Flynn effect and ability differentiation. Possible causes of this association are discussed.     

A Jensen effect on dysgenic fertility: An analysis involving the National Longitudinal Survey of Youth

In this study we attempt to determine whether dysgenic fertility is associated with the Jensen effect. This is investigated with respect to a US population representative sample of 8110 individuals from the National Longitudinal Survey of Youth for whom there exists complete data on IQ and fertility. In addition to the general sample, the sample was also broken out by race and sex so as to examine whether or not the Jensen effect manifested amongst different sub-populations. The method of correlated vectors revealed significant Jensen effects in five of the seven samples, and in all cases the effect was in a direction indicating that subtests with higher g-loadings were associated with larger dysgenic fertility gradients. The magnitude of the difference between Spearman’s ρ and Pearson’s r was non-significant in all cases, suggesting that biasing factors were minimally influencing the result. This finding suggests that dysgenesis occurs on the ‘genetic g’ at the heart of the Jensen effect nexus, unlike the Flynn effect, which is ‘hollow’ with respect to g. Finally, the finding is discussed in the context of two converging lines of evidence indicating that genotypic IQ or ‘genetic g’ really has been declining over the last century.