Barrier properties of Al2O3 and alucone coatings and nanolaminates on flexible biopolymer films

Thin atomic layer deposited (ALD) Al₂O₃ coatings are efficient barriers against gases and vapors. Al₂O₃ coatings are, however, brittle and straining them generates defects that impair barrier properties. Flexibility of ALD-grown Al₂O₃ coatings on biopolymer substrates can be improved by separating thinner Al₂O₃ layers with inorganic-organic alucone layers. The number and size of defects were smaller for these nanolaminates compared to the thick Al₂O₃ films after straining, and hence straining deteriorated the oxygen barrier properties less when applied to the laminates than when applied to the Al₂O₃ coatings.     

An optimisation strategy in a digital environment applied to neonatal chest imaging

The aim of this study was to find the optimum tube voltage for neonatal chest imaging in computed radiography. The study was designed to take full advantage of the benefits of digital imaging, for example, by comparing the tube voltages at constant effective dose. A phantom study using a living rabbit was first conducted. Images were collected at tube voltages ranging from 40 to 90 kV(p). The reproduction of four structures (central vessels, peripheral vessels, carina and thoracic vertebrae) was rated by 10 radiologists. The reproduction of both central and peripheral vessels was relatively independent of tube voltage. The carina was better reproduced at higher tube voltages whereas the opposite was true for the thoracic vertebrae. Based on the higher importance of the reproduction of the carina it was decided that 90 kV(p) was the optimal tube voltage. To validate the result from the phantom study, a follow-up study was conducted in which images of neonates collected at the tube voltage regularly used at Sahlgrenska University Hospital (70 kV(p)) were compared with images collected at the tube voltage proposed by the phantom study. The follow-up study confirmed the results from the phantom study that the reproduction of the carina was better at 90 than at 70 kV(p). In conclusion, for neonatal chest imaging-given the same effective dose-90 kVp gives better reproduction of important structures than the regularly used 70 kV(p).     

On the rate of growth and extent of the steady damage accumulation phase in repeated impact tests

In the paper, data of repeated impact tests performed on seven laminates of different lay-up and thickness are used to illustrate how the damage index (DI), a damage variable recently introduced by the authors to monitor the range of the penetration process in thick laminates, can be applied in case of repeated impact tests to get information on the rate of initial steady damage accumulation as well as on the onset of severe damage modes.Curves of the rate of growth of the DI in the steady phase (ΔDI/ΔN) vs. the normalised impact energy (ratio of the impact energy E_i and the laminate penetration threshold P_n) show no significant damage accumulation besides initial specimen indentation for impact energies below 0.2P_n. For intermediate levels of impact energy, repeated impact tests are characterised by an initial region of steady damage accumulation followed by an abrupt change in the rate of damage growth a few impacts before laminate perforation. For higher impact energies (E_i/P_n > 0.4–0.45), no phase of steady damage accumulation is present, suggesting that severe damage mechanisms take place from the very first impacts. Values of the DI at the end of the steady phase (DI_unsteady) are shown to be rather peculiar to each laminate regardless of the impact energy used in the tests and therefore may be used to get a first indication of the laminate performance to repeated impacts. The extent of the steady phase may also be used to compute the total energy absorbed by the laminate in the steady damage accumulation phase (E_aTOT__steady).     

Cultural, sociofamilial, and psychological resources that inhibit psychological distress in African Americans exposed to stressful life events and race-related stress.

This study tested a sociocultural model of stress and coping in a sample of 215 African Americans. Psychological resources (optimism, ego resilience) were modeled as a "nested self" (S. E. Hobfoll, 2001), supported by social resources (family adaptability and cohesion) and cultural resources (racial pride, religiosity). Race-related stress was a significantly more powerful risk factor than stressful life events for psychological distress. Structural equation modeling results confirmed the hypotheses that psychological resources had a significant direct effect in minimizing psychological distress, and social resources had a significant stress-suppressing effect on race-related stress. Theoretical and practical implications for counseling psychologists are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

High-level reasoning and base-rate use: Do we need cue-competition to explain the inverse base-rate effect?

Previous accounts of the inverse base-rate effect (D. L. Medin & S. M. Edelson, see record 1988-31640-001) have revolved around the concept of cue-competition. In this article, the authors propose that high-level reasoning in the form of an eliminative inference mechanism may contribute to the effect. A quantitative implementation of this idea demonstrates that it has the power by itself to produce the pattern of base-rate effects in the Medin and Edelson (1988) design. Four predictions are derived that contradict the predictions by attention to distinctive input (ADIT; J. K. Kruschke, see record 1996-02680-001), up to date the most successful account of the inverse base-rate effect. Results from 3 experiments disconfirm the predictions by ADIT and demonstrate the importance of high-level reasoning in designs of the Medin and Edelson kind. Implications for the interpretation of the inverse base-rate effect and the attention-shifting mechanisms presumed by ADIT are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Coated contacts: a strain approach

A strain approach for the design of coated contacts is described, allowing a simple evaluation of the risk of coating failure, once the elastic modulus of the coating and the substrate and the coating thickness are known. Examples are provided for hard and soft coatings. The approach is shown to be particularly useful for hard coatings, where failure is mainly related to tensile longitudinal stresses at the interface. Results from the proposed strain approach compare well with data from a standard stress analysis. Finally, the level of approximation introduced by evaluating the strain field for the reference Hertzian case is discussed, showing that the error introduced is not acceptable.