Nano-scale behavior of irradiated nano-structured alloys

Future fast neutron fusion and fission nuclear systems will be subjected to levels of radiation damage from fast neutrons which is significantly higher than the current generation of nuclear power stations. This will require innovative materials solutions to allow long term mechanical stability of reactors. One proposed class of materials are nanostructured alloys where the large number of interfaces allow for recombination defects and reduce the degree of radiation hardening seen. However their response under irradiation has not thoroughly been studied. In this work, two irradiated nanostructured alloys have been studied W-5%Re in both a nanostructured and annealed variant and a novel Hf-Ti-Ta-V-Zr high entropy alloy. I will outline the benefits nanostructured materials offer under irradiation and some of the problems and challenges in measuring their mechanical properties after irradiation and relating this to the nano-structure using XRD, TEM, HR-EBSD and atom probe tomography. Rolled tungsten 5 wt% rhenium sheet was studied in two microstructural variants: (a) as received with a high dislocation density (mean value of 1.4×1014lines/m2), measured using HR-EBSD, and pancake shaped grains with a thickness of≈200nm and (b) annealed at 1400oC for 24 hours to produce equiaxed grains with average grain size of ≈90 µm and low dislocation density (with a mean value of 4.8×1013 lines/m2). Both materials were ion implanted with 2MeV W+ ions at 300oC to damage levels from 0.07, to 33 displacements per atom (dpa). Nanoindentation was used to measure the change in hardness after implantations. Irradiation induced hardening saturated in the as-received material at an increase of 0.4dpa from the unimplanted hardness of 8GPa at 0.4dpa. In the annealed material saturation does not occur by 13dpa and the hardness change of 1.3GPa from the unimplanted hardness of 6.2GPa was over four times higher. At 33dpa both material types showed a further increase in hardening. In these samples Atom probe tomography showed clustering of Re in ≈4nm precipitates with a rhenium concentration of ≈11%. In both cases the number density and volume fraction are similar at ≈3100 x1000/µm3 and volume fraction of ≈13%. These differences in radiation response are likely to be due to the high damage sink density in the as-received microstructure in the form of dislocation networks, as even in the as-received material the average grain size is too large to provide sufficient sinks. Initially this provides a large sink network for radiation damage resulting in less hardening in the rolled material. However at 33dpa the formation of rhenium clusters occurs at similar levels in both material conditions. These dominate the hardening mechanisms and result in secondary hardening at high damage levels. The difficulties in extracting hardness values from 200nm deep ion implanted layers will be discussed, with reference to minimizing the influence of the substrate material and how changes in pile up effects in irradiated materials can change mechanical responses, and proposed methods to minimize these. High entropy alloys have been proposed as potential nuclear materials as high configurational entropy may provide resistance to radiation damage. We have produced a novel high entropy alloy (Hf-Ti-Ta-V-Zr) in which is single phase on casting but two high entropy phases (one bcc and one hcp) are produced during heat treatment. This material then has a nano-lamella structure with an average lamella thickness of 200nm. Samples of the as cast single phase material, the dual phase high entropy alloy and single crystal vanadium were ion irradiated with V+ ions at 300oC to a dose of 5e14 ions/cm2. In the vanadium control samples the hardness as measured using CSM-nanoindentation was seen to increase from 2GPa in the unimplanted condition to 3.5GPa in the ion irradiated condition. The high entropy alloy in both the as cast and heat treated condition showed no increase in hardness after irradiation, demonstrating the intrinsic resistance to radiation damage of HEA’s. These studies show the ability of nanostructured alloys to have improved irradiation hardening resistance over conventional alloys. However challenges still remain in the production of large scale engineering components in such materials

Core information sets for informed consent to surgical interventions:baseline information of importance to patients and clinicians

Abstract Background Consent remains a crucial, yet challenging, cornerstone of clinical practice. The ethical, legal and professional understandings of this construct have evolved away from a doctor-centred act to a patient-centred process that encompasses the patient’s values, beliefs and goals. This alignment of consent with the philosophy of shared decision-making was affirmed in a recent high-profile Supreme Court ruling in England. The communication of information is central to this model of health care delivery but it can be difficult for doctors to gauge the information needs of the individual patient. The aim of this paper is to describe ‘core information sets’ which are defined as a minimum set of consensus-derived information about a given procedure to be discussed with all patients. Importantly, they are intended to catalyse discussion of subjective importance to individuals. Main body The model described in this paper applies health services research and Delphi consensus-building methods to an idea orginally proposed 30 years ago. The hypothesis is that, first, large amounts of potentially-important information are distilled down to discrete information domains. These are then, secondly, rated by key stakeholders in multiple iterations, so that core information of agreed importance can be defined. We argue that this scientific approach is key to identifying information important to all stakeholders, which may otherwise be communicated poorly or omitted from discussions entirely. Our methods apply systematic review, qualitative, survey and consensus-building techniques to define this ‘core information’. We propose that such information addresses the ‘reasonable patient’ standard for information disclosure but, more importantly, can serve as a spring board for high-value discussion of importance to the individual patient. Conclusion The application of established research methods can define information of core importance to informed consent. Further work will establish how best to incorporate this model in routine practice

Core information sets for informed consent to surgical interventions:baseline information of importance to patients and clinicians

Abstract Background Consent remains a crucial, yet challenging, cornerstone of clinical practice. The ethical, legal and professional understandings of this construct have evolved away from a doctor-centred act to a patient-centred process that encompasses the patient’s values, beliefs and goals. This alignment of consent with the philosophy of shared decision-making was affirmed in a recent high-profile Supreme Court ruling in England. The communication of information is central to this model of health care delivery but it can be difficult for doctors to gauge the information needs of the individual patient. The aim of this paper is to describe ‘core information sets’ which are defined as a minimum set of consensus-derived information about a given procedure to be discussed with all patients. Importantly, they are intended to catalyse discussion of subjective importance to individuals. Main body The model described in this paper applies health services research and Delphi consensus-building methods to an idea orginally proposed 30 years ago. The hypothesis is that, first, large amounts of potentially-important information are distilled down to discrete information domains. These are then, secondly, rated by key stakeholders in multiple iterations, so that core information of agreed importance can be defined. We argue that this scientific approach is key to identifying information important to all stakeholders, which may otherwise be communicated poorly or omitted from discussions entirely. Our methods apply systematic review, qualitative, survey and consensus-building techniques to define this ‘core information’. We propose that such information addresses the ‘reasonable patient’ standard for information disclosure but, more importantly, can serve as a spring board for high-value discussion of importance to the individual patient. Conclusion The application of established research methods can define information of core importance to informed consent. Further work will establish how best to incorporate this model in routine practice

Customizing hybrid products

We explore how the convergence of the digital and physical into hybrid products leads to new possibilities for customization. We report on a technology probe, a hybrid advent calendar with both paper form and digital layers of content, both of which were designed to be customizable. We reveal how over two hundred active users adapted its physical and digital aspects in various ways, some anticipated and familiar, but others surprising. This leads us to contribute concepts to help understand and design for hybrid customization – the idea of broad customization spanning physical and digital; end-to-end customization by different stakeholders along the value chain for a product; and the combination of these into customization maps

Distributed N-body Simulation on the Grid Using Dedicated Hardware

We present performance measurements of direct gravitational N -body simulation on the grid, with and without specialized (GRAPE-6) hardware. Our inter-continental virtual organization consists of three sites, one in Tokyo, one in Philadelphia and one in Amsterdam. We run simulations with up to 196608 particles for a variety of topologies. In many cases, high performance simulations over the entire planet are dominated by network bandwidth rather than latency. With this global grid of GRAPEs our calculation time remains dominated by communication over the entire range of N, which was limited due to the use of three sites. Increasing the number of particles will result in a more efficient execution. Based on these timings we construct and calibrate a model to predict the performance of our simulation on any grid infrastructure with or without GRAPE. We apply this model to predict the simulation performance on the Netherlands DAS-3 wide area computer. Equipping the DAS-3 with GRAPE-6Af hardware would achieve break-even between calculation and communication at a few million particles, resulting in a compute time of just over ten hours for 1 N -body time unit. Key words: high-performance computing, grid, N-body simulation, performance modellingComment: (in press) New Astronomy, 24 pages, 5 figure

Operational analysis of school-based delivery models to vaccinate children against influenza.

Large-scale immunisation programmes against seasonal influenza are characterised by logistical challenges related to the need for vaccinating large cohorts of people in a short amount of time. Careful operational planning of resources is essential for a successful implementation of such programmes. We focused on the process of child vaccination in schools and analysed the staffing and workflow aspects of a school-aged children vaccination programme in England. Our objectives were to document vaccination processes and analyse times and costs associated with different models deployed across England. We collected data through direct non-participatory observations. Statistical data analysis enabled us to identify potential factors influencing vaccine delivery time and informed the development of a tool to simulate vaccination sessions. Using this tool, we carried out scenario analyses and explored trade-offs between session times and costs in different settings. Our work ultimately supported the local implementation of school-based vaccination

Location-based Virtual Reality Experiences for Children:Japan-UK knowledge exchange network: Tokyo Workshop

This is the programme, abstracts and speaker bios for the Location-based Virtual Reality Experiences for Children:Japan-UK knowledge exchange network: Tokyo Workshop