Engineering self-organising helium bubble lattices in tungsten

The self-organisation of void and gas bubbles in solids into a superlattices is an intriguing nanoscale phenomenon. Despite the discovery of these lattices 30 years ago, the atomistics behind the ordering mechanisms responsible for the formation of these nanostructures are yet to be fully elucidated. Here we report on the direct observation via transmission electron microscopy of the formation of bubble lattices under He+ ion bombardment. By careful control of the irradiation conditions, it has been possible to engineer the bubble size and spacing of the superlattice leading to important conclusions about the significance of vacancy supply in determining the physical characteristics of the system. Furthermore, no bubble lattice alignment was observed in the directions pointing to a key driving mechanism for the formation of these ordered nanostructures being the two-dimensional diffusion of self-interstitial atoms

Development of Commercial Applications of a FAPY Alloy

The Fe-16 at. (8.5 wt) % Al alloy, known as FAPY, has been identified as a superior material for heating element applications. However, while the 15-lb heats melted at the Oak Ridge National Laboratory (ORNL) could be processed into wire, the large heat melted at Hoskins Manufacturing Company (Hoskins) could not be processed under commercial processing conditions. The primary objective of the Cooperative Research and Development Agreement (CRADA) was to demonstrate that wire of the FAPY alloy could be produced under commercial conditions from air-induction-melted (AIM) heats. The specific aspects of this CRADA included: (1) Melting 15-lb heats by AIM or vacuum-induction melting (VIM) at ORNL. (2) Development of detailed processing steps including warm drawing and annealing temperature and time during cold-drawing steps. (3) Melting of 1400-lb heats at Hoskins by the Exo-Melt{trademark} process and their chemical analysis and microstructural characterization. (4) Development of tensile properties of sections of ingots from the large heats in the ascast, hot-worked, and hot- and cold-worked conditions. (5) Microstructural characterization of cast and wrought structures and the fractured specimens. (6) Successful demonstration of processing of AIM heats at Hoskins to heating element wire. The aspects of this CRADA listed above have demonstrated that the FAPY alloy of the desired composition can be commercially produced by AIM by the use of the Exo-Melt{trademark} process. Furthermore, it also demonstrated that the wire processing steps developed for 15-lb heats at ORNL can be successfully applied to the production of wire from the large AIM heats

Characterization of mechanisms of hot deformation of as-cast nickel aluminide alloy

The hot deformation behavior of as-cast $Ni_3Al$ alloy has been characterized on the basis of its flow stress variation obtained by isothermal constant true strain rate compression testing in the temperature range 1100-1250°C and strain rate range $0.001-10 \hspace{2mm}s^-1$. The mechanisms of hot working have been evaluated using four generations of materials modeling techniques, which included shape of stress-strain curves, kinetic analysis, processing maps and dynamical systems approach. The material exhibited a steady-state flow behavior at slower strain rates but flow softening associated sometimes with broad oscillations, was observed at higher strain rates. The flow stress data did not obey the kinetic rate equation over the entire regime of testing but a good fit has been obtained in the intermediate range of temperatures (1150-1200°C). In this range, a stress exponent value of 6.5 and an apparent activation energy of about 750 kJ/mol have been evaluated. Microstructural investigations have shown that the matrix $\gamma'$ phase undergoes dynamic recovery in the presence of harder $\gamma$ colonies The processing maps revealed four different domains out of which three are interpreted to represent cracking processes. The fourth domain, which has a peak efficiency of about 44%, occurred at $1250^oC/0.001 \hspace{2mm} s^-1$. Microstructural observations revealed that this domain represents dynamic recrystallization (DRX) of $\gamma$ phase and is desirable for hot working the material. The material exhibits flow instabilities when deformed in the intermediate temperature regime at strain rates higher than $1 \hspace{2mm}s^-1$ and these are manifested as shear localization

Statin intolerance: Now a solved problem

Statins are the most effective and widely used drugs for treating dyslipidemia, a major risk factor for coronary heart disease. These are one of the safest hypolipidemic drugs but many patients are bound to discontinue statins due to their side effects. Hepatotoxicity, myotoxicity and peripheral neuropathy are important out of them. Discontinuation of statins leads to dylipidemia and its grave consequences. Hence, there should be enough strategies for statin intolerant patients, so that they can be saved from these consequences. These side effects can be avoided by the awareness of certain factors viz. potential drug interactions and dose adjustment according to patho-physiology of the patient. Baseline investigations for liver function and muscle toxicity should be done before initiating statin therapy. Here, we are discussing various options for statin intolerant hyperlipidemic patients such as lower and intermittent dosing of statins, alternate hypolipidemic drugs, red yeast rice, supplementation with coenzyme Q10 and vitamin D. A number of hypolipidemic drugs are in trial phases and hold promise for statin intolerant patients