Dynamic precipitation during cyclic deformation of an underaged Al-Cu alloy

The cyclic deformation behavior of Al-4Cu alloy containing shear-resistant particles was investigated systematically as a function of precipitate state. Pronounced cyclic hardening was observed in the under aged Al-4Cu-0.05Sn (wt.%) alloy strained under various imposed plastic strain amplitudes at room temperature. Such cyclic hardening is absent from the longer aging treatments. Microstructural characterization reveals that the pronounced cyclic hardening of the under aged alloy is due to the dynamic precipitation of GP zones. The dynamic precipitation occurs during all the cyclic loading process and only at the peak stress, where the hardening increment from dynamic precipitation saturates, does strain localization occur which is soon followed by failure of the material. The dynamic precipitation of GP zones has a positive effect on the low cycle fatigue performance of this alloy, and can significantly elevate the strength of this alloy without loss in ductility. Experiments performed to test the dependence of the cyclic hardening on plastic strain amplitude and strain-rate illustrate a relatively strain-rate independent and strain amplitude dependent behavior. Such kinetic behavior is approximately consistent with that expected if the GP zone formation is controlled by the vacancies production process during plastic deformation.     

Molecular regulators of resolution of inflammation: potential therapeutic targets in the reproductive system

Inflammatory processes are central to reproductive events including ovulation, menstruation, implantation and labour, while inflammatory dysregulation is a feature of numerous reproductive pathologies. In recent years, there has been much research into the endogenous mechanisms by which inflammatory reactions are terminated and tissue homoeostasis is restored, a process termed resolution. The identification and characterisation of naturally occurring pro-resolution mediators including lipoxins and annexin A1 has prompted a shift in the field of anti-inflammation whereby resolution is now observed as an active process, triggered as part of a normal inflammatory response. This review will address the process of resolution, discuss available evidence for expression of pro-resolution factors in the reproductive tract and explore possible roles for resolution in physiological reproductive processes and associated pathologies.     

Cracking due to Localized Hot Shock

Results are presented for the cracking to be expected when a sudden temperature increase is applied over a localized region on a surface of a brittle solid. A localized temperature increase is applied to the surface of a body whose interior is initially at uniform temperature. A three-part analysis is conducted: (i) for the evolving temperature distribution, (ii) for the evolving thermal stresses induced by the nonuniform temperature field, and (iii) for stress intensity factors of cracks oriented either parallel to or perpendicular to the surface and initiated at times when the stresses are critical. Plane-strain and axisymmetric versions of the problems are considered. For the plane-strain problem, the complete trajectory of the crack is determined under the assumption that its tip advances maintaining a pure mode I field at all times. Conditions for excluding cracking due to localized hot shock are given.     

An International Marine-Atmospheric 222Rn Measurement Intercomparison in Bermuda Part I: NIST Calibration and Methodology for Standardized Sample Additions

As part of an international ²²²Rn measurement intercomparison conducted at Bermuda in October 1991, NIST provided standardized sample additions of known, but undisclosed (“blind”) ²²²Rn concentrations that could be related to U.S. national standards. The standardized sample additions were obtained with a calibrated ²²⁶Ra source and a specially-designed manifold used to obtain well-known dilution factors from simultaneous flow-rate measurements. The additions were introduced over sampling periods of several hours (typically 4 h) into a common streamline on a sampling tower used by the participating laboratories for their measurements. The standardized ²²²Rn activity concentrations for the intercomparison ranged from approximately 2.5 Bq · m⁻³ to 35 Bq · m⁻³ (of which the lower end of this range approached concentration levels for ambient Bermudian air) and had overall uncertainties, approximating a 3 standard deviation uncertainty interval, of about 6 % to 13 %. This paper describes the calibration and methodology for the standardized sample additions.     

Engineering an Anti‐Graffiti System: A Study in Industrial Product Design

The objective of this work was to develop products for the anti‐graffiti market using a product design framework that takes into account the company core practices and meets customer expectations. Product development comprised several concurrent steps including market research and analysis to determine the market potential using a Quality Functional Deployment tool. From market research it was estimated that anti‐graffiti products had significant potential within Australia. A range of technical and quality parameters were tested. The Hildebrand and Hansen solubility parameters, viscosity and diffusivity estimates were mainly used for technical evaluation of products. An iterative process was used throughout in conjunction with parameter restraints to meet environmental sustainability, waste reduction and minimize resource consumption. The result was a cost effective product, tailored to customer expectations.     

Heuristics and biases in the "eyeballing" of data: the effects of context on intuitive correlation assessment

For a wide variety of real-world decisions, people must examine numerical tables and intuitively assess the correlations that exist among meaningful variables. The normative properties of correlation coefficients suggest that such decisions should be unaffected by perceptual factors (e.g., changes in row and column locations), semantic factors (e.g., the referents of the numbers), or certain transformations of the variables (e.g., adding a constant or multiplying by a constant). Four experiments demonstrated that judgments based on perceived correlations violate these normative properties. A general model of intuitive covariation assessment was proposed to explain the observed biases. Estimation of this model at the aggregate and individual levels suggested that no single heuristic is consistent with all of the results. Instead, the existence of several qualitatively different types of heuristics was supported. The distribution of individual-level decision rules across types of heuristics was systematically related to contextual factors.     

High-power long-wavelength (λ~11.5 μm) quantum cascadelasers operating above room temperature

High-temperature operation (T=320 K) of quantum cascade lasers has been extended to 11.5-μm wavelengths with high performances. Peak-pulsed optical power of 55 mW is obtained at 300 K with a high T ₀=172 K, in good agreement with our theoretical model     

A randomized double-blind comparison of the effects on systemic calcium homeostasis of topical calcitriol (3 micrograms/g) and calcipotriol (50 micrograms/g) in the treatment of chronic plaque psoriasis vulgaris

Calcitriol and calcipotriol are effective treatments for psoriasis, although the two have never been directly compared. We compared the efficacy and toxicity of each agent in 24 patients with moderately extensive chronic plaque psoriasis, who were randomized in double-blind fashion to apply 90 g per week of either calcitriol (3 micrograms/g) ointment or calcipotriol (50 micrograms/g) ointment over an 8-week period. Mean PASI in patients applying calcitriol fell from 13 to 8.8 (p < 0.05) and in patients applying calcipotriol from 14.9 to 4.7 (p < 0.005). The reduction was significantly greater in the calcipotriol-treated group (p < 0.05). There was a small increase in serum ionized calcium in the calcipotriol-treated group (from 1.21 mmol/L to 1.25 mmol/L, p < 0.05) but no effect on calcium homeostasis in the calcitriol group.