An examination of the hydrological system of a sand dam during the dry season leading to water balances

To address water scarcity in semi-arid regions, rainfall and runoff need to be captured and stored locally before they are lost to the sea. This can be done using a sand dam which consists of a reinforced wall constructed during the dry season across a seasonal riverbed. However it is unclear whether their main utility is to store water in the sand that is also trapped behind them, or to facilitate aquifer recharge. This paper aims to answer this question by the calculation of a water balance in three sand dams in Kenya to quantify the amount of water transferred between the sand dam and the surrounding aquifer system. The components of the water balance were derived from extensive field monitoring. Water level monitoring in piezometers installed along the length of the sand deposits enabled calculation of the hydraulic gradient and hence the lateral flow between the different reaches of the sand dam. In one sand dam water was gained consistently through the dry season, in one it was lost, and in the third it was lost almost all the time except for the early dry season in the upper part of the trapped sand. In conclusion sand dams should not be treated as isolated water storage structures

Impact of fouling, cleaning and faecal contamination on the separation of water from urine using thermally driven membrane separation

In this study, membrane distillation is evaluated as a technology for non-sewered sanitation, using waste heat to enable separation of clean water from urine. Whilst membrane fouling was observed for urine, wetting was not evident and product water quality met the proposed discharge standard, despite concentration of the feed. Fouling was reversible using physical cleaning, which is similar to previous membrane studies operating without pressure as the driving force. High chemical oxygen demand reduction was achieved following faecal contamination, but mass transfer was impeded and wetting occurred which compromised permeate quality, suggesting upstream intervention is demanded to limit the extent of faecal contamination

Well flow and dilution measurements for characterization of vertical hydraulic conductivity structure of a carbonate aquifer

The paper aims to characterize vertical variations in horizontal hydraulic properties in a fractured carbonate aquifer, the Cretaceous Chalk in East Yorkshire, UK. Two approaches are used: an inverse model of well flow applied to flow logs of pumped open wells, and open well dilution testing. In this case study, transmissivity in the unconfined part of the aquifer is dominated by the highly permeable zone of water table fluctuation, where carbonate dissolution has occurred enhancing fracture aperture; a similar enhanced permeability zone is present at the top of the aquifer where it is confined beneath glacial deposits, although periglacial physical weathering during Quaternary cold periods, rather than carbonate dissolution, is responsible. The aquifer is also shown to contain deeper permeable horizons of stratigraphic origin, which are better developed in the unconfined section

Measuring proteins in H2O using 2D-IR spectroscopy; pre-processing steps and applications towards a protein library

The ability of two-dimensional infrared (2D-IR) spectroscopy to measure the amide I band of proteins in H2O rather than D2O-based solvents by evading the interfering water signals has enabled in-vivo studies of proteins under physiological conditions and in biofluids. Future exploitation of 2D-IR in analytical settings, from diagnostics to protein screening, will however require comparisons between multiple datasets, necessitating control of data collection protocols to minimise measurement-to-measurement inconsistencies. Inspired by analytical spectroscopy applications in other disciplines, we describe a workflow for pre-processing 2D-IR data that aims to simplify spectral cross-comparisons. Our approach exploits the thermal water signal that is collected simultaneously with, but is temporally separated from the amide I response to guide custom baseline correction and spectral normalisation strategies before combining them with Principal Component noise reduction tools. Case studies show that application of elements of the pre-processing workflow to previously-published data enables improvements in quantification accuracy and detection limits. We subsequently apply the complete workflow in a new pilot study, testing the ability of a prototype library of 2D-IR spectra to quantify the four major protein constituents of blood serum in a single, label-free measurement.  These advances show progress towards the robust data handling strategies that will be necessary for future applications of 2D-IR for pharmaceutical or biomedical applications

In situ characterization of CD4+ T cell behavior in mucosal and systemic lymphoid tissues during the induction of oral priming and tolerance

The behavior of antigen-specific CD4+ T lymphocytes during initial exposure to antigen probably influences their decision to become primed or tolerized, but this has not been examined directly in vivo. We have therefore tracked such cells in real time, in situ during the induction of oral priming versus oral tolerance. There were marked contrasts with respect to rate and type of movement and clustering between naive T cells and those exposed to antigen in immunogenic or tolerogenic forms. However, the major difference when comparing tolerized and primed T cells was that the latter formed larger and longer-lived clusters within mucosal and peripheral lymph nodes. This is the first comparison of the behavior of antigen-specific CD4+ T cells in situ in mucosal and systemic lymphoid tissues during the induction of priming versus tolerance in a physiologically relevant model in vivo

The multiple uses of water derived from managed aquifer recharge systems in Kenya and India

‘Multiple-use services’ (MUS) takes into account the fact that households use water for both domestic and for productive uses. This paper is the first to determine how managed aquifer recharge (MAR) systems are a form of MUS. Two cases were studied in India and in Kenya. In the Kenyan case, sand dams are the form of MAR, and in India check dams and infiltration ponds of various scales are used. Through observations, interviews, and water quality data, it is possible to describe how the communities access the water from these infrastructures in multiple ways for different uses, according to their water needs and the characteristics of the different access points. MAR involves harvesting rainwater and retaining run-off water into the dry season thus increasing the amount of available water and enabling diversification of water uses. It should therefore be considered as an option by water managers aiming to develop water resources meeting both the domestic and productive needs of communities.Engineering and Physical Sciences Research Council (EPSRC): EP/N009711/1 and Natural Environment Research Council (NERC):NE/R003351/1

Senescence and Inflammatory Markers for Predicting Clinical Progression in Parkinson's Disease: The ICICLE-PD Study.

BACKGROUND: Cognitive decline is a frequent complication of Parkinson's disease (PD) and the identification of predictive biomarkers for it would help in its management. OBJECTIVE: Our aim was to analyse whether senescence markers (telomere length, p16 and p21) or their change over time could help to better predict cognitive and motor progression of newly diagnosed PD patients. We also compared these senescence markers to previously analysed markers of inflammation for the same purpose. METHODS: This study examined the association of blood-derived markers of cell senescence and inflammation with motor and cognitive function over time in an incident PD cohort (the ICICLE-PD study). Participants (154 newly diagnosed PD patients and 99 controls) underwent physical and cognitive assessments over 36 months of follow up. Mean leukocyte telomere length and the expression of senescence markers p21 and p16 were measured at two time points (baseline and 18 months). Additionally, we selected five inflammatory markers from existing baseline data. RESULTS: We found that PD patients had shorter telomeres at baseline and 18 months compared to age-matched healthy controls which also correlated to dementia at 36 months. Baseline p16 levels were associated with faster rates of motor and cognitive decline over 36 months in PD cases, while a simple inflammatory summary score at baseline best predicted cognitive score over this same time period in PD patients. CONCLUSION: Our study suggests that both inflammatory and senescence markers (p16) are valuable predictors of clinical progression in PD patients.This study was supported by a Newcastle upon Tyne Hospital Trust (Brain Research Unit PD0612) grant to GS. ICICLE-PD is funded by Parkinson’s UK (grant no J-0802, G-1301) and supported by the National Institute for Health Research (NIHR) Newcastle Biomedical Research Centre in Ageing and Chronic Disease and the Biomedical Research Unit in Lewy Body Dementia based at Newcastle upon Tyne Hospitals NHS Foundation Trust and Newcastle University (CM-R) and the National Institute for Health Research (NIHR) Cambridge Biomedical Research Centre (146281). This work was also supported by grants from the Academy of Medical Sciences, UK, the Rosetrees Trust, and the Stevenage Biosciences Catalyst. CHWG is supported by a RCUK/UKRI Research Innovation Fellowship awarded by the Medical Research Council (MR/R007446/1). RAB is an NIHR Senior Investigator (NF-SI-0616-10011) and is supported by the WT/MRC Stem Cell Institute (203151/Z/16/Z

Managing power dissipation in closed-loop reverse electrodialysis to maximise energy recovery during thermal-to-electric conversion

Whilst the efficiency of reverse electrodialysis (RED) for thermal-to-electrical conversion has been theoretically demonstrated for low-grade waste heat, the specific configuration and salinity required to manage power generation has been less well described. This study demonstrates that operating RED by recycling feed solutions provides the most suitable configuration for energy recovery from a fixed solution volume, providing a minimum unitary cost for energy production. For a fixed membrane area, recycling feeds achieves energy efficiency seven times higher than single pass (conventional operation), and with an improved power density. However, ionic transport, water flux and concentration polarisation introduce complex temporal effects when concentrated brines are recirculated, that are not ordinarily encountered in single pass systems. Regeneration of the concentration gradient at around 80% energy dissipation was deemed most economically pragmatic, due to the increased resistance to mass transport beyond this threshold. However, this leads to significant exergy destruction that could be improved by interventions to better control ionic build up in the dilute feed. Further improvements to energy efficiency were fostered through optimising current density for each brine concentration independently. Whilst energy efficiency was greatest at lower brine concentrations, the work produced from a fixed volume of feed solution was greatest at higher saline concentrations. Since the thermal-to-electrical conversion proposed is governed by volumetric heat utilisation (distillation to reset the concentration gradient), higher brine concentrations are therefore recommended to improve total system efficiency. Importantly, this study provides new evidence for the configuration and boundary conditions required to realise RED as a practical solution for application to sources of low-grade waste heat in industr

Tree planting in organic soils does not result in net carbon sequestration on decadal timescales

Tree planting is increasingly being proposed as a strategy to combat climate change through carbon (C) sequestration in tree biomass. However, total ecosystem C storage that includes soil organic C (SOC) must be considered to determine whether planting trees for climate change mitigation results in increased C storage. We show that planting two native tree species (Betula pubescens and Pinus sylvestris ), of widespread Eurasian distribution, onto heather (Calluna vulgaris ) moorland with podzolic and peaty podzolic soils in Scotland, did not lead to an increase in net ecosystem C stock 12 or 39 years after planting. Plots with trees had greater soil respiration and lower SOC in organic soil horizons than heather control plots. The decline in SOC cancelled out the increment in C stocks in tree biomass on decadal timescales. At all four experimental sites sampled, there was no net gain in ecosystem C stocks 12–39 years after afforestation—indeed we found a net ecosystem C loss in one of four sites with deciduous B. pubescens stands; no net gain in ecosystem C at three sites planted with B. pubescens ; and no net gain at additional stands of P. sylvestris . We hypothesize that altered mycorrhizal communities and autotrophic C inputs have led to positive ‘priming’ of soil organic matter, resulting in SOC loss, constraining the benefits of tree planting for ecosystem C sequestration. The results are of direct relevance to current policies, which promote tree planting on the assumption that this will increase net ecosystem C storage and contribute to climate change mitigation. Ecosystem‐level biogeochemistry and C fluxes must be better quantified and understood before we can be assured that large‐scale tree planting in regions with considerable pre‐existing SOC stocks will have the intended policy and climate change mitigation outcomes