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Ho J.C.M.,The University of Queensland | Lai M.H.,University of Hong Kong
Proceedings of the Institution of Civil Engineers: Structures and Buildings | Year: 2014

High-strength concrete (HSC) columns are usually provided with heavy confining steel within the potential plastic hinge region to restore flexural ductility. However, as the effectiveness of confining steel decreases with the concrete strength, the required confining steel content for high-strength concrete columns becomes very large, which causes steel congestion in the proximity of beam–column joints. A better method is to adopt a concrete-filled-steel-tube (CFST) column, which uses a hollow steel tube to confine high-strength concrete. Compared with ordinary reinforcement, concrete-filled-steel-tube columns provide a more uniform confining pressure to the concrete core and reduce steel congestion. Nonetheless, a major shortcoming of concrete-filled-steel-tube columns is that the imperfect interface bonding occurs at the elastic stage as steel dilates more than concrete in compression. This adversely affects the confinement of the steel tube and decreases the elastic strength and modulus. To resolve the problem, it is proposed in this study to use external steel confinement in the forms of rings and ties to restrict the dilation of the steel tube. For verification, a series of uniaxial compression tests on externally confined concrete-filled-steel-tube columns was performed. Theoretical models for predicting the uniaxial load-carrying capacity of ring-confined concrete-filled-steel-tube columns were also developed. © 2014, Thomas Telford Services Ltd. All rights reserved. Source

We review theories of phosphorescence in cyclometalated complexes. We focus primarily on pseudooctahedrally coordinated t2g6 metals (e.g., [Os(II)(bpy)3]2+, Ir(III)(ppy)3 and Ir(III)(ptz)3) as, for reasons that are explored in detail, these show particularly strong phosphorescence. We discuss both first principles approaches and semi-empirical models, e.g., ligand field theory. We show that together these provide a clear understanding of the photophysics and in particular the lowest energy triplet excitation, T1. In order to build a good model relativistic effects need to be included. The role of spin-orbit coupling is well-known, but scalar relativistic effects are also large - and are therefore also introduced and discussed. No expertise in special relativity or relativistic quantum mechanics is assumed and a pedagogical introduction to these subjects is given. Once both scalar relativistic effects and spin-orbit coupling are included, time dependent density functional theory (TDDFT) provides quantitatively accurate predictions of the radiative decay rates of the substates of T1 in phosphorescent organotransition-metal complexes. We describe the pseudo-angular momentum model, and show that it reproduces the key experimental findings. For example, this model provides a simple explanation of the relative radiative rates of the substates of T1, which differ by orders of magnitude. Special emphasis is placed on materials with potential applications as active materials in organic light-emitting diodes (OLEDs) and principles for the design of new complexes are identified on the basis of the insights provided by the theories reviewed. We discuss the remaining theoretical challenges, which include deepening our understanding of solvent effects and, vitally, understanding and predicting non-radiative decay rates. © 2015 Elsevier B.V. Source

News Article
Site: http://phys.org/biology-news/

PhD student Genevieve Phillips at The University of Queensland's Queensland Brain Institute said the reef was one of the planet's most visually diverse environments in terms of light availability and the colours and patterns on the animals living there. "We studied the visual systems of the labrids, a large family of fish that includes wrasses – which are mainly predatory – and parrotfish – which tend to eat coral and algae," she said. "Many animals have visual systems that are tuned to the specific wavelengths of light that availablein their environment, so fish that live in rivers 'see' differently from fish living at the bottom of the ocean." Ms Phillips said the team, which includes scientists from The University of Maryland, studied the different types of opsins in fishes' eyes. "Opsins are light-sensitive proteins in the photoreceptors that absorb light at specific wavelengths," she said. This absorption was the first step in the process of "seeing" an image. Researchers could learn which colours an animal could potentially see by studying the different classes and quantities of opsins in its eyes. "Many labrids live in the same environment with similar light availability, so you could expect that their visual systems would be fairly similar," Ms Phillips said. "But we found that the repertoire of opsins they express is actually very different. "In general, most of the opsins found in the fishes' eyes were sensitive to the green-blue region of the spectrum, which is typical of many reef fish, as it is the dominant light available to fish on coral reefs. "However, some of the labrids appeared to have specialised in opsins sensitive to orange-red light." Ms Phillips said this could help these fish find prey against a predominantly red-brown background. "The more we understand about what fish can see, and how this relates to their behaviour, the more we will understand about biodiversity on the Great Barrier Reef," she said. The study is published in Molecular Biology and Evolution. Explore further: Capturing an octopus-eye view of the Great Barrier Reef More information: Genevieve A.C. Phillips et al. Multiple Genetic Mechanisms Contribute to Visual Sensitivity Variation in the Labridae, Molecular Biology and Evolution (2015). DOI: 10.1093/molbev/msv213

Gucciardi D.F.,Curtin University | Gucciardi D.F.,The University of Queensland | Hanton S.,Cardiff Metropolitan University | Gordon S.,University of Western Australia | And 2 more authors.
Journal of Personality | Year: 2015

Mental toughness has received increased scholarly attention in recent years, yet conceptual issues related to its (a) dimensionality, (b) nomological network, and (c) traitness remain unresolved. The series of studies reported in this article were designed to examine these three substantive issues across several achievement contexts, including sport, education, military, and the workplace. Five studies were conducted to examine these research aims-Study 1: N=30; Study 2: calibration sample (n=418), tertiary students (n=500), athletes (n=427), and employees (n=550); Study 3: N=497 employees; Study 4: N=203 tertiary students; Study 5: N=115 army candidates. Collectively, the results of these studies revealed that mental toughness may be best conceptualized as a unidimensional rather than a multidimensional concept; plays an important role in performance, goal progress, and thriving despite stress; and can vary and have enduring properties across situations and time. This series of studies provides a foundation for further basic and applied research of mental toughness across various achievement contexts. © 2014 Wiley Periodicals, Inc. Source

News Article | September 12, 2016
Site: http://www.techtimes.com/rss/sections/environment.xml

Top Scientific Minds You Probably Never Heard Of What sets our home planet apart from others are the lush forests and jungles, grasslands, swamps, expansive deserts and sprawling savannahs that blanket its terrain. However, each year, Earth has lesser and lesser of these natural spots because of human activity and disturbance, a new report has revealed. Earth's wilderness is rapidly eroding. Approximately 10 percent of the planet's wilderness — the biological and ecological landscapes that are typically free of human disturbance — has vanished in the last two decades alone, the new study says. In order to determine the loss of the planet's wilderness, scientists from the Wildlife Conservation Society evaluated satellite and survey data recorded since the 1990s. By definition, wilderness landscapes begin to cease not when humans settle there, but when human activity disturbs ecosystems via land conversion, large-scale infrastructure projects and land conversion. In the end, researchers discovered that globally, 1.2 million square miles of wilderness — twice the size of the state of Alaska — have been lost in the last 20 years. James Watson, study lead author and an expert from Australia's The University of Queensland, says the amount of wilderness that has vanished in just two decades is staggering. In fact, the greatest loss in wilderness occurred in South America at 30 percent, and in Africa at 14 percent, they found. A few areas such as the Northwestern Congolian Lowland Forests, as well as the Northern New Guinea Lowland Rain and Freshwater Swamp Forests ecoregions, have lost almost all of their former wilderness. Such negative losses on wilderness could have strong impacts on indigenous communities, wildlife and climate change, researchers say. What's more, the destruction of a small chunk of ecosystem could negatively affect the rest, especially because wilderness regions are interdependent and interconnected. When it comes to restoring the lost wilderness, Watson says it cannot be done. Once wilderness areas are gone, the ecological processes behind these ecosystems are also gone. "And it never comes back to the state it was," says Watson. On the other hand, the new study offers good news: much of Earth's remaining wilderness or nearly 80 percent is still made up of large chunks of land. This is crucial for species living in these regions because if habitats become disturbed by clear-cutting or roads, the animals are less likely to survive. And there is still hope to abate further losses. Between 2005 and 2012, statistics show that deforestation rates in Brazil decreased to 70 percent because of conservation and protection efforts by soybean farmers and cattle ranchers in the country. Watson says it is clear that more is required to strengthen the protection of Earth's remaining wilderness. This includes basic conservation, as well as transforming grasslands and forests into reserves and protected areas. Details of the new report are published in the journal Current Biology. © 2016 Tech Times, All rights reserved. Do not reproduce without permission.

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