Assessing moisture in porous traditional building materials

Historic England is often asked for advice on damp problems in historic and traditional buildings. Whilst many different methods are commonly used to assess damp problems in walls, all have some drawbacks. There is lack of agreement over how they should be used and little information about how they compare one with another. This project developed a common methodology in the laboratory to compare the performance of a range of invasive and non-invasive moisture measurement methods used to assess moisture in porous masonry. The findings suggested that most of the measurement techniques can provide good semi-quantitative estimates of moisture levels in porous traditional building materials

The zoogeomorphology of case‐building caddisfly: Quantifying sediment use

Caddisfly (Trichoptera) larvae are an abundant and widespread aquatic insect group characterised by the construction of silk structures, including nets and cases. Case‐building caddisfly have the potential to modify the sorting and mobility of sand and fine gravel via; 1) case construction, resulting in altered sediment properties; 2) transporting sediment incorporated into cases over the river bed and; 3) changing the structure of river‐beds via burrowing. To investigate these mechanisms, it is necessary to understand the mass, size distribution and spatial variability of sediment use by case‐building caddisfly larvae.We quantified the mineral sediment used by individuals and communities of case‐building caddisfly in 27 samples, from three sites on a gravel‐bed stream. The mass and size distribution of sediment in individual cases varied between taxa (mass = 0.001 – 0.83 g, D50 = 0.17 – 4 mm). The mean mass of sediment used by the caddisfly community was 38 g m‐2 and varied locally. Sediment use was predominantly coarse sand (D50 = 1 mm). 64% of sediment use was attributable to Agapetus fuscipes (Glossosomatidae).Due to within‐species variability in case mass, the abundance of most taxa, including A. fuscipes, was only weakly associated with the mass of sediment used at the river scale. Whilst the caddisfly community used a small percentage of the total sediment available (average 2.99% of the 1‐1.4 mm size fraction), A. fuscipes used more fine sediment in their cases at sites where it was more available. Despite variability in local habitat, all sites supported diverse case‐building caddisfly communities utilising mineral sediment. Consequently, geomorphological effects of case‐building caddisfly are potentially widespread. The results provide novel insights into the specific grain sizes and quantities of fine sediment particles (g m‐2) used by caddisfly larvae, which represents an important step towards understanding their zoogeomorphic activities

Cu(II) mediates kinetically distinct, non-amyloidogenic aggregation of amyloid-β peptides

Cu(II) ions are implicated in the pathogenesis of Alzheimer disease by influencing the aggregation of the amyloid-β (Aβ) peptide. Elucidating the underlying Cu(II)-induced Aβ aggregation is paramount for understanding the role of Cu(II) in the pathology of Alzheimer disease. The aim of this study was to characterize the qualitative and quantitative influence of Cu(II) on the extracellular aggregation mechanism and aggregate morphology of Aβ(1–40) using spectroscopic, microelectrophoretic, mass spectrometric, and ultrastructural techniques. We found that the Cu(II):Aβ ratio in solution has a major influence on (i) the aggregation kinetics/mechanism of Aβ, because three different kinetic scenarios were observed depending on the Cu(II):Aβ ratio, (ii) the metal:peptide stoichiometry in the aggregates, which increased to 1.4 at supra-equimolar Cu(II):Aβ ratio; and (iii) the morphology of the aggregates, which shifted from fibrillar to non-fibrillar at increasing Cu(II):Aβ ratios. We observed dynamic morphological changes of the aggregates, and that the formation of spherical aggregates appeared to be a common morphological end point independent on the Cu(II) concentration. Experiments with Aβ(1–42) were compatible with the conclusions for Aβ(1–40) even though the low solubility of Aβ(1–42) precluded examination under the same conditions as for the Aβ(1–40). Experiments with Aβ(1–16) and Aβ(1–28) showed that other parts than the Cu(II)-binding His residues were important for Cu(II)-induced Aβ aggregation. Based on this study we propose three mechanistic models for the Cu(II)-induced aggregation of Aβ(1–40) depending on the Cu(II):Aβ ratio, and identify key reaction steps that may be feasible targets for preventing Cu(II)-associated aggregation or toxicity in Alzheimer disease

The Rapid Exchange of Zinc (2+) Enables Trace Levels to Profoundly Influence Amyloid-beta Misfolding and Dominates Assembly Outcomes in Cu (2+)/Zn (2+) Mixtures

This work was supported by the Biotechnology and Biological Sciences Research Council Project GrantBB/M023877/1 and Quota Studentship

Sediment source fingerprinting: benchmarking recent outputs, remaining challenges and emerging themes

Abstract: Purpose: This review of sediment source fingerprinting assesses the current state-of-the-art, remaining challenges and emerging themes. It combines inputs from international scientists either with track records in the approach or with expertise relevant to progressing the science. Methods: Web of Science and Google Scholar were used to review published papers spanning the period 2013–2019, inclusive, to confirm publication trends in quantities of papers by study area country and the types of tracers used. The most recent (2018–2019, inclusive) papers were also benchmarked using a methodological decision-tree published in 2017. Scope: Areas requiring further research and international consensus on methodological detail are reviewed, and these comprise spatial variability in tracers and corresponding sampling implications for end-members, temporal variability in tracers and sampling implications for end-members and target sediment, tracer conservation and knowledge-based pre-selection, the physico-chemical basis for source discrimination and dissemination of fingerprinting results to stakeholders. Emerging themes are also discussed: novel tracers, concentration-dependence for biomarkers, combining sediment fingerprinting and age-dating, applications to sediment-bound pollutants, incorporation of supportive spatial information to augment discrimination and modelling, aeolian sediment source fingerprinting, integration with process-based models and development of open-access software tools for data processing. Conclusions: The popularity of sediment source fingerprinting continues on an upward trend globally, but with this growth comes issues surrounding lack of standardisation and procedural diversity. Nonetheless, the last 2 years have also evidenced growing uptake of critical requirements for robust applications and this review is intended to signpost investigators, both old and new, towards these benchmarks and remaining research challenges for, and emerging options for different applications of, the fingerprinting approach

A new era for understanding amyloid structures and disease

The aggregation of proteins into amyloid fibrils and their deposition into plaques and intracellular inclusions is the hallmark of amyloid disease. The accumulation and deposition of amyloid fibrils, collectively known as amyloidosis, is associated with many pathological conditions that can be associated with ageing, such as Alzheimer disease, Parkinson disease, type II diabetes and dialysis-related amyloidosis. However, elucidation of the atomic structure of amyloid fibrils formed from their intact protein precursors and how fibril formation relates to disease has remained elusive. Recent advances in structural biology techniques, including cryo-electron microscopy and solid-state NMR spectroscopy, have finally broken this impasse. The first near-atomic-resolution structures of amyloid fibrils formed in vitro, seeded from plaque material and analysed directly ex vivo are now available. The results reveal cross-β structures that are far more intricate than anticipated. Here, we describe these structures, highlighting their similarities and differences, and the basis for their toxicity. We discuss how amyloid structure may affect the ability of fibrils to spread to different sites in the cell and between organisms in a prion-like manner, along with their roles in disease. These molecular insights will aid in understanding the development and spread of amyloid diseases and are inspiring new strategies for therapeutic intervention

A comparison of standard and realistic curing conditions of natural hydraulic lime repointing mortar for damp masonry: Impact on laboratory evaluation

Environmental conditions can affect the curing and performance of lime mortars. Especially in the case of natural hydraulic lime (NHL) mortars to be used for repointing in exposed conditions, it is essential to assess what if any differences these environmental conditions would make to mortar properties through laboratory evaluations before repointing work begins. This study considers a specific historic environment: traditional masonry exposed to high humidity and rainfall, with a particular focus on Devon. Realistic curing conditions (as likely found on-site) of 15 °C, 85% RH, representing an average of summer climate in Devon were compared with standard recommended laboratory conditions of 20 °C, 65% RH. A range of mixes, representing some conservation pointing mortars, was prepared using NHL 2 (St Astier), quartz sand, and crushed Portland limestone in 1:3 and 1:2 binder to aggregate ratios. The influence of curing conditions on carbonation depth, strength development, internal textural structure, pore structure and water uptake at 28 and 90 days is discussed (called here early and medium ages) and the response of NHL mortars to this humid environment during evaporation and salt crystallisation have been assessed. Results show that significant differences are found in laboratory evaluations of mechanical properties of the same NHL mortar exposed to different curing conditions especially at an early age and for mortar made with quartz sand. Laboratory evaluation should be made on samples cured under realistic conditions if information on the early to medium-term (up to 90 days) characteristics of NHL mortar is required. Overall, realistic humid curing conditions help NHL mortars gain good internal structure more quickly, minimising the risk of early failure of pointing mortar exposed in a harsh humid environment

Population-level zoogeomorphology: the case of the Eurasian badger (Meles meles L.)

The zoogeomorphological impact of burrowing animals varies in time and space as a result of the particular life history traits of the organisms involved, the patchy distribution of habitat resources, and fluctuations in population size. Such ecological complexity presents a major challenge for biogeomorphologists wishing to upscale from individuals to populations. Using a unique ecological data set for Eurasian badgers (Meles meles L.) in Wytham Woods, Oxfordshire, UK, we show that direct zoogeomorphological impact (soil displacement during sett excavation) is constrained by fluctuations in overall population size. Modeled digging rates for individual badgers (0.19-4.51 m3 yr-1) varied depending on the ecological function of the sett they are associated with, and we estimate that the whole population has displaced 304-601 ± 72 m3 of soil during the construction of 64 setts. This represents an overall excavation rate of 6.7-19.4 m3 (6.0-17.5 t) yr-1 in sett areas or 1.42-4.12 g m-2 yr-1 when averaged over the whole 424 ha woodland. As well as direct soil displacement, badger digging exposes material that is initially susceptible to erosion by water relative to undisturbed and litter-covered soils. Over time, setts become stabilized, representing unique landforms that persist in the landscape for decades to centuries

A comparison of standard and realistic curing conditions of natural hydraulic lime repointing mortar for damp masonry: Impact on laboratory evaluation

Environmental conditions can affect the curing and performance of lime mortars. Especially in the case of natural hydraulic lime (NHL) mortars to be used for repointing in exposed conditions, it is essential to assess what if any differences these environmental conditions would make to mortar properties through laboratory evaluations before repointing work begins. This study considers a specific historic environment: traditional masonry exposed to high humidity and rainfall, with a particular focus on Devon. Realistic curing conditions (as likely found on-site) of 15 °C, 85% RH, representing an average of summer climate in Devon were compared with standard recommended laboratory conditions of 20 °C, 65% RH. A range of mixes, representing some conservation pointing mortars, was prepared using NHL 2 (St Astier), quartz sand, and crushed Portland limestone in 1:3 and 1:2 binder to aggregate ratios. The influence of curing conditions on carbonation depth, strength development, internal textural structure, pore structure and water uptake at 28 and 90 days is discussed (called here early and medium ages) and the response of NHL mortars to this humid environment during evaporation and salt crystallisation have been assessed. Results show that significant differences are found in laboratory evaluations of mechanical properties of the same NHL mortar exposed to different curing conditions especially at an early age and for mortar made with quartz sand. Laboratory evaluation should be made on samples cured under realistic conditions if information on the early to medium-term (up to 90 days) characteristics of NHL mortar is required. Overall, realistic humid curing conditions help NHL mortars gain good internal structure more quickly, minimising the risk of early failure of pointing mortar exposed in a harsh humid environment