A Comparative study into the performance of hot mixed and lime putty mortars with additions of metakaolin and brick dust pozzolans.

This paper explores the properties of mortars where the principle binder is calcium hydroxide. Two distinct forms of the binder were used: a ‘hot mix’ consisting of quicklime (calcium oxide), and a slaked and matured lime putty mortar. The modifications of properties exhibited by the two binders with and without the addition of pozzolans, brick dust and metakaolin were established. This study has relevance because of the lack of empirical data on the performance of modified mortars of these types. The experimental evaluation of properties including the mortar compressive and flexural strengths and the bond strengths obtained with brick demonstrated that although the hot mixed lime mortars expressed some advantages in terms of porosity over the putty-based counterparts, there is no significant difference in performance regardless of the pozzolan added

Revitalising Collyweston limestone slate production by artificial freeze/thaw splitting

Extraction of limestone roofing slate from Collyweston was an industry which was considered extinct by the early 1990′s, with building repairs relying on wholesale recycling of roofing from demolished buildings. Traditionally stone extracted from the mines was exposed to natural cycles of freeze/thaw to facilitate splitting. Work was undertaken over several years to investigate the resources available and whether these could be artificially frozen to produce slates. The work identified a freeze/thaw regime which could be used to produce roofing slates for historic buildings and which were used in the Historic England restoration of Apethorpe Palace. Mining of the Collyweston limestone stone has now resumed and uses artificial freezing to achieve production of slates which is economically feasible due to the faster process time

The Palace of Westminster Courtyards Project: Sourcing Stone for Repair and Conservation

The Palace of Westminster, commonly known as the Houses of Parliament, serves as the meeting place of the House of Commons and the House of Lords and is situated on the north bank of the River Thames in London, England. The site is part of the UNESCO Westminster World Heritage Site. The building was constructed of magnesian limestone, selected following a nationwide survey of building stones carried out by a Government Select Committee. However, some of this stone began to decay soon after construction in the mid 1800s. As the majority of the stonework has survived very well the aim of the work was to source a demonstrably durable material with characteristics which align with the majority of the existing stonework. Samples were taken from the building for petrographic analysis in order to identify compatible material in quarries, either working or which could be re-opened. Durability of the magnesian limestone was assessed using both accepted tests and novel methodology. Large scale walls were constructed in the laboratory and exposed to accelerated frost weathering with realistic temperature parameters. The logistical problems with sourcing the original building material, the nature of the transport and the masons' unfamiliarity with the stone may all have played a part in undermining its durability. When magnesian limestone is properly selected and used correctly, its reputation for being of poor durability is largely unfounded. Suitable sources for replacement stone were located which provided several options for both immediate and long-term sourcing for repair and conservation

Functional PTB phosphate transporters are present in streptophyte algae and early diverging land plants

International audienceTwo inorganic phosphate (Pi) uptake mechanisms operate in streptophytes and chloro-phytes, the two lineages of green plants. PHOSPHATE TRANSPORTER B (PTB) proteins are hypothesized to be the Na + /Pi symporters catalysing Pi uptake in chlorophytes, whereas PHOSPHATE TRANSPORTER 1 (PHT1) proteins are the H + /Pi symporters that carry out Pi uptake in angiosperms. PHT1 proteins are present in all streptophyte lineages. However, Pi uptake in streptophyte algae and marine angiosperms requires Na + influx, suggesting that Na + /Pi symporters also function in some streptophytes. We tested the hypothesis that Na + /Pi symporters exist in streptophytes. We identified PTB sequences in streptophyte genomes. Core PTB proteins are present at the plasma membrane of the liverwort Marchantia polymorpha. The expression of M. polymorpha core PTB proteins in the Saccharomyces cerevisiae pho2 mutant defective in high-affinity Pi transport rescues growth in low-Pi environments. Moreover, levels of core PTB mRNAs of M. polymorpha and the streptophyte alga Coleochaete nitellarum are higher in low-Pi than in Pi-replete conditions, consistent with a role in Pi uptake from the environment. We conclude that land plants inherited two Pi uptake mechanisms-mediated by the PTB and PHT1 proteins, respectively-from their streptophyte algal ancestor. Both systems operate in parallel in extant early diverging land plants

Report on the Third Workshop on Sustainable Software for Science: Practice and Experiences (WSSSPE3)

This report records and discusses the Third Workshop on Sustainable Software for Science: Practice and Experiences (WSSSPE3). The report includes a description of the keynote presentation of the workshop, which served as an overview of sustainable scientific software. It also summarizes a set of lightning talks in which speakers highlighted to-the-point lessons and challenges pertaining to sustaining scientific software. The final and main contribution of the report is a summary of the discussions, future steps, and future organization for a set of self-organized working groups on topics including developing pathways to funding scientific software; constructing useful common metrics for crediting software stakeholders; identifying principles for sustainable software engineering design; reaching out to research software organizations around the world; and building communities for software sustainability. For each group, we include a point of contact and a landing page that can be used by those who want to join that group's future activities. The main challenge left by the workshop is to see if the groups will execute these activities that they have scheduled, and how the WSSSPE community can encourage this to happen

Report on the Third Workshop on Sustainable Software for Science: Practice and Experiences (WSSSPE3)

This report records and discusses the Third Workshop on Sustainable Software for Science: Practice and Experiences (WSSSPE3). The report includes a description of the keynote presentation of the workshop, which served as an overview of sustainable scientific software. It also summarizes a set of lightning talks in which speakers highlighted to-the-point lessons and challenges pertaining to sustaining scientific software. The final and main contribution of the report is a summary of the discussions, future steps, and future organization for a set of self-organized working groups on topics including developing pathways to funding scientific software; constructing useful common metrics for crediting software stakeholders; identifying principles for sustainable software engineering design; reaching out to research software organizations around the world; and building communities for software sustainability. For each group, we include a point of contact and a landing page that can be used by those who want to join that group’s future activities. The main challenge left by the workshop is to see if the groups will execute these activities that they have scheduled, and how the WSSSPE community can encourage this to happe

Report on the 3rd Workshop on Sustainable Software for Science: Practice and Experiences (WSSSPE3)

This report records and discusses the Third Workshop on Sustainable Software for Science: Practice and Experiences (WSSSPE3). The report includes a description of the keynote presentation of the workshop, which served as an overview of sustainable scientific software. It also summarizes a set of lightning talks in which speakers highlighted to-the-point lessons and challenges pertaining to sustaining scientific software. The final and main contribution of the report is a summary of the discussions, future steps, and future organization for a set of self-organized working groups on topics including developing pathways to funding scientific software; constructing useful common metrics for crediting software stakeholders; identifying principles for sustainable software engineering design; reaching out to research software organizations around the world; and building communities for software sustainability. For each group, we include a point of contact and a landing page that can be used by those who want to join that group's future activities. The main challenge left by the workshop is to see if the groups will execute these activities that they have scheduled, and how the WSSSPE community can encourage this to happen