Effect of heat treatment on delayed hydride cracking in Zr-2.5 Wt Pct Nb

The effect of heat treatments on delayed hydride cracking (DHC) in Zr-2.5 wt pct Nb has been studied. Crack velocities were measured in hydrided specimens, which were cooled from solution-treatment temperatures at different rates by water-quenching, oil-quenching, liquid-nitrogen quenching, and furnace cooling. The resulting hydride size, morphology, and distributions were examined by optical metallography. It was found that fast cooling rates, which produce very finely dispersed hydrides, result in higher crack growth rates and a stronger dependence of the crack velocity on the applied-stress intensity factor. Also, the incubation period before cracking commences was found to be relatively short for specimens with fine hydrides, whereas specimens with coarse hydrides required considerably longer incubation periods. These results can be explained by rapid growth of preexisting hydrides within the crack-tip plastic zone. In addition, different solution temperatures were used to investigate the effect of the continuity of the grain-boundary phase(β-phase) on the crack velocity. Transmission electron microscopy was used to examine the structure of this grain-boundary phase. It was found that for heat treatments, which destroyed theβ-phase continuity, the crack velocity was significantly reduced, as would be expected from the theory of enhanced diffusion through grain boundaries.     

A biological perspective on the structure and function of caseins and casein micelles

Caseins belong to a larger group of secreted calcium phosphate-binding phosphoproteins that have a natively unfolded conformation. Nearly all members of the group are involved in aspects of calcium phosphate biology and nearly all have recognition sites for phosphorylation by the Golgi protein kinase. In the caseins these are often close together in the primary structure, forming the so-called phosphate centres. Certain highly phosphorylated phosphopeptides derived from the calcium-sensitive caseins will combine with amorphous calcium phosphate to form defined chemical complexes called calcium phosphate nanoclusters. Both the substructure of casein micelles and the partition of salts in milk can be explained quantitatively by the ability of the calcium-sensitive caseins to sequester calcium phosphate and form nanocluster-like structures. A simple stability rule for milk can be derived by applying equilibrium thermodynamics to the process of calcium phosphate sequestration. In principle, the stability rule can be extended to problems of instability encountered in milk-processing operations and to the formulation of other types of high calcium foods.     

Performance of locality-aware topologies for peer-to-peer live streaming

This study is concerned with the effect of overlay network topology on the performance of live streaming peer-to-peer systems. The study focuses on the evaluation of topologies which are aware of the delays experienced between different peers on the network. Metrics are defined which assess the topologies in terms of delay, bandwidth usage and resilience to peer drop-out. Several topology creation algorithms are tested and the metrics are measured in a simple simulation testbed. This gives an assessment of the type of gains, which might be expected from locality awareness in peer-to-peer networks.     

Bicontinuous emulsions stabilized solely by colloidal particles

Recent large-scale computer simulations suggest that it may be possible to create a new class of soft solids, called 'bijels', by stabilizing and arresting the bicontinuous interface in a binary liquid demixing via spinodal decomposition using particles that are neutrally wetted by both liquids. The interfacial layer of particles is expected to be semi-permeable; hence, if realized, these new materials would have many potential applications, for example, as micro-reaction media. However, the creation of bijels in the laboratory faces serious obstacles. In general, fast quench rates are necessary to bypass nucleation, so that only samples with limited thickness can be produced, which destroys the three-dimensionality of the putative bicontinuous network. Moreover, even a small degree of unequal wettability of the particles by the two liquids can lead to ill-characterized, 'lumpy' interfacial layers and therefore irreproducible material properties. Here, we report a reproducible protocol for creating three-dimensional samples of bijel in which the interfaces are stabilized by essentially a single layer of particles. We demonstrate how to tune the mean interfacial separation in these bijels, and show that mechanically, they indeed behave as soft solids. These characteristics and their tunability will be of great value for microfluidic applications.     

Nutraceutical therapies for degenerative joint diseases: a critical review

There is growing recognition of the importance of nutritional factors in the maintenance of bone and joint health, and that nutritional imbalance combined with endocrine abnormalities may be involved in the pathogenesis of osteoarthritis (OA) and osteochondritis dissecans (OCD). Despite this, dietary programs have played a secondary role in the management of these connective tissue disorders. Articular cartilage is critically dependent upon the regular provision of nutrients (glucose and amino acids), vitamins (particularly vitamin C), and essential trace elements (zinc, magnesium, and copper). Therefore, dietary supplementation programs and nutraceuticals used in conjunction with non-steroidal, anti-inflammatory drugs (NSAIDs) may offer significant benefits to patients with joint disorders, such as OA and OCD. This article examines the available clinical evidence for the efficacy of nutraceuticals, antioxidant vitamin C, polyphenols, essential fatty acids, and mineral cofactors in the treatment of OA and related joint disorders in humans and veterinary species. This article also attempts to clarify the current state of knowledge. It also highlights the need for additional targeted research to elucidate the changes in nutritional status and potential alterations to the expression of plasma membrane transport systems in synovial structures in pathophysiological states, so that current therapy and future treatments may be better focused.     

Classics in megaproject management: A structured analysis of three major works

The paper explores three texts in the field of megaproject management that intersubjectively, in terms of community sentiment, might be considered ‘classics’. We deploy four criteria for a structured analysis that determines if the status of the works in question may be considered classic. The works examined are Megaprojects and Risk: An Anatomy of Ambition by Flyvbjerg, Bruzelius and Rothengatter; (2003) The Anatomy of Major Projects by Morris and Hough (1987) and Industrial Megaprojects by Merrow (2011). Based on these works we conclude with a prospectus for future research that will serve to develop the field of research into megaproject management.