Mechanical Properties of Hydroxyapatite-Zirconia Compacts Sintered by Two Different Sintering Methods

Microwave sintering is traditionally employed to reduce the sintering temperature required to densify powder compacts. The effect of microwave heating on hydroxyapatite (HA)-zirconia (ZrO2) green bodies has been investigated in order to understand how microwave energy may affect the physical and mechanical properties of the resultant densified composites. Laboratory synthesised nano-sized HA and a commercial nano-sized ZrO2 powder have been ball milled to create mixtures containing 0-5 wt% ZrO2 loadings. Compacts were microwave sintered at either 700, 1000 or 1200°C with a 1 h hold time. Comparative firings were also performed in a resistive element furnace using the same heating profile in order to assess the differences between conventional and microwave heating on the physical, mechanical and microstructural properties of the composites. Samples sintered at 700°C show little sign of densification with open porosities of approximately 50%. Composites conventionally sintered at 1000°C were between 65 and 75% dense, whereas the samples microwave sintered at this temperature were between 55 and 65% dense. Samples sintered at 1200°C showed the greatest degree of densification (\u3e80%) with a corresponding reduction in open porosities. TCP generation occurred as a consequence of sintering at 1200°C, even with 0 wt% ZrO2, and increased degradation of the HA phase to form significant amounts of TCP occurred with increasing additions of ZrO2, along with increasing open porosity. Nanosized ZrO2 prevents the densification of the HA matrix by effectively pinning grain boundaries and this effect is more pronounced in the MS materials. Similar strengths are achieved between the microwave and conventionally sintered samples. Greater amount of open porosity and pore interconnectivity are seen in the MS samples, which are considered to be useful for biomedical applications as they can promote osteo-integration. © 2009 Springer Science+Business Media, LLC

A test method and deterioration model for joints and cracks in concrete slabs

This paper reports on the development of a laboratory test method to assess the deterioration of concrete cracks and joints under low intensity, high cycle loading, typical of that found in industrial flooring, external hardstandings and rigid pavements. The half-scale prism specimen enables the impact of crack geometry, reinforcement and load magnitude to be assessed in relation to load transfer deterioration, without the need for full scale testing. Each element of the testing procedure has been developed to represent site conditions in respect to crack development, loading and support. A selection of the test results are presented which indicate that joint/crack deterioration consists of four distinct phases, each controlled by a different mechanism of material degradation. This information can be used to enhance understanding of joint/crack behaviour and their failure mechanisms, hence improving design and maintenance procedures

Simplified laboratory assessment of subgrade performance parameters for mechanistic design of pavement foundations

With the increasing agenda for sustainability, the UK is attempting to move away from the empirical design of pavement foundations to develop a performance specification approach to facilitate analytical design. For analytical design the measurement of the subgrade performance parameters of resilient modulus and resistance to permanent deformation are required. These parameters ideally need to be assessed concurrently under loading and environmental conditions similar to those the materials will experience in the field. To date, measurement of these parameters is largely confined to research laboratories using cyclic triaxial testing with advanced on sample strain measurement. This apparatus is considered too complicated for routine commercial use, hence this potentially limits the implementation of laboratory performance evaluation for routine pavement foundation design. A previous program of cyclic triaxial testing on clay subgrades indicated a series of useful correlations between strength and permanent deformation behavior (via a threshold stress), and material resilient modulus at this threshold. This paper reviews the previous work and utilizing these correlations presents data from tests on three different clay materials performed to develop simplified equipment and procedures for the routine measurement of the required design parameters. It is shown that simple pseudo-static tests can measure a subgrade modulus for a simplified performance based design. It re-evaluates the previous data (in the light of the recent work) to show a boundary correlation that may allow a shear strength based parameter to control (in design) the onset of permanent deformation, and details how long-term subgrade water content changes can be accommodated

Closing the feedback loop: A systems approach to supporting community-wide behaviour change in non-domestic buildings

The work was partly funded by the SMARTSPACES project (http://smartspaces.eu) co-funded by the European Commission within the CIP ICT Policy Support Programme (Grant agreement no. 297273).Energy consumption is notoriously invisible to building users. Communicating energy performance to users presents a significant opportunity to support behaviour change. Access to near real-time consumption data makes ubiquitous energy performance feedback systems a realistic possibility. Non-domestic building energy performance is a complicated issue, so providing simple, intelligible feedback can be difficult. Communicating what building users are supposed to do with the information is still more so. A true closed-loop feedback system must include both communication of information to users and a means for users to affect the building to which the information pertains. This paper reports the design and use of a novel information system to facilitate a true feedback loop between a community of building stakeholders (users, energy professionals, researchers) and 25 pilot buildings. The buildings were equipped to communicate energy performance in near real time via a user-friendly ‘dashboard’ built on a sophisticated system of automated data capture, energy consumption modelling, predictive statistical analysis and visualisation. The ‘dashboard’ allowed casual users to access information easily via a simple happy/sad performance indicator whilst more “data-philic” users were able to click through to a data rich, easy-to-use interface. Users were also provided with access to a digital social platform enabling transparent discussion of energy performance with reference to the objective data. Results show that the ‘dashboard’ and digital social platform components are each valuable in their own right but in combination they produced a system whereby users could identify and solve energy and water performance problems effectively and efficiently

Prediction of retinopathy progression using deep learning on retinal images within the Scottish screening programme

Background/AimsNational guidelines of many countries set screening intervals for diabetic retinopathy (DR) based on grading of the last screening retinal images. We explore the potential of deep learning (DL) on images to predict progression to referable DR beyond DR grading, and the potential impact on assigned screening intervals, within the Scottish screening programme.MethodsWe consider 21346 and 247233 people with T1DM and T2DM respectively each contributing on average 4.8 and 4.4 screening intervals of which 1339 and 4675 intervals concluded with a referable screening episode. Information extracted from fundus images using DL were used to predict referable status at the end of interval and its predictive value in comparison to screening-assigned DR grade was assessed.ResultsThe DL predictor increased the AUC in comparison to a predictor using current DR grades from 0.809 to 0.87 for T1DM and from 0.825 to 0.87 for T2DM. Expected sojourn time – the time from becoming referable to being rescreened - was found to be 3.4 (T1DM) and 2.7 (T2DM) weeks less for a DL-derived policy compared to the current recall policy.ConclusionsWe showed that, compared to using the current retinopathy grade, DL of fundus images significantly improves the prediction of incident referable retinopathy before the next screening episode. This can impact screening recall interval policy positively, for example, by reducing the expected time with referable disease for a fixed workload - which we show as an exemplar. Additionally, it could be used to optimise workload for a fixed sojourn time

Entrepreneurship and Urban Success: Toward a Policy Consensus

Like all politics, all entrepreneurship is local. Individuals launch firms and, if successful, expand their enterprises to other locations. But new firms must start somewhere, even if their businesses are conducted largely or exclusively on the Internet. Likewise, policymakers at local and state levels increasingly recognize that entrepreneurship is the key to building and sustaining their economies\u27 growth. Although this is a seemingly obvious proposition, it represents something of a departure from past thinking about how local, state, or regional economies grow. Historically, state and local policymakers have put their energies into trying to attract existing firms from somewhere else, either to relocate to a particular area or to build new facilities there. Such smokestack chasing - or, in this cleaner era, simply firm chasing - often has degenerated into what is essentially a zero-sum game for the national economy. When one city or state offers tax breaks or other financial inducements to encourage firms to locate new plants or headquarters, and succeeds, some other city or state loses out in the process. Local, state, and regional economic development centered on entrepreneurship, however, is a fundamentally different phenomenon. The formation and growth of new firms, especially those built around new products or ways of doing things, wherever this occurs, is clearly a positive sum game, not just for the locality, but for the nation as a whole. This essay provides a guide to policymakers and citizens to what is known about the effects of various local and state policies aimed at fostering entrepreneurially driven growth. There is also much we do not know; thus, the essay identifies subjects that require further research

Assessing Asthma Symptoms in Adolescents and Adults : Qualitative Research Supporting Development of the Asthma Daily Symptom Diary

We thank the members of the US Food and Drug Administration’s Qualification Review Team for their feedback during the development of the ADSD. Source of financial support: Funding for this research was provided by the following PRO Consortium member firms: Actelion; Amgen; AstraZeneca; Boehringer-Ingelheim; Forest Laboratories; Genentech; GlaxoSmithKline; Ironwood Pharmaceuticals; Janssen, Merck, Sharp & Dohme Corp.; Novartis; Pfizer; and Sanofi. In addition, Critical-Path Institute’s PRO Consortium is supported by Critical-Path Public-Private Partnerships (grant no. 1U18FD005320) from the US Food and Drug Administration.Peer reviewedPublisher PD