An Isotopic and Mineralogical Investigation of Concrete Decay

Concrete is a man made rock composed of aggregate bound rigidly in a paste composed of hydrous cementitious minerals. It is a porous and permeable medium on both the macro and microscopic scales. This study has revealed that the phases present in cement pastes, in particular portlandite, can have random or preferred orientations at the cement paste to aggregate interface. The micro-mineralogy of the cement paste to aggregate bond interface in concretes is texturally complex and concrete mixing techniques can effect the phases present at the interface and the density of the interface. In a core of concrete from a road bridge undergoing active decay, pyrite and pyrrhotine were found to have oxidised by interaction with percolating rainwater. The sulphate released by the oxidised iron sulphides has been taken into solution and eventually precipitated in large spherical cavities in the cement paste, in the form of the mineral ettringite. Water flowing through the structure has possibly been more significant in leaching gypsum from the cement paste and depositing it in the cavities as ettringite. The ettringite has a whisker crystal habit, and has nucleated heterogenetically from solution on the walls of the spherical cavities. The whisker crystal habit is propagated by a screw dislocation in the crystal, the concentration of the elements required for growth being in the solution at low enough concentrations as to limit multi-directional nucleation. The fluid that has percolated through the structure oxidising the iron sulphides has become hyper-alkaline due to the leaching of portlandite from the cement paste. This fluid has reacted with atmospheric carbon dioxide to produce a calcitic crust on the top of the road bridge and a stalactitic growth on the underside of the road bridge. Similar crusts and stalactites were collected from other concrete structures in the Midland Valley of Scotland, and analysed for delta18C and delta18O values. The delta13C values are in the range of -18.8‰ to -28.9‰ PDB. The delta18O values are in the range of +8.5‰ to +16.5‰ SMOW. The calcites formed by the interaction of the hyper-alkaline fluids that have percolated through the structures, with atmospheric carbon dioxide (delta13C = PDB, delta18O = +41‰ SMOW). The stalactites have formed by the production of successive calcite layers, by the diffusion of carbon dioxide into the bulbs of hyper-alkaline solutions as they emerge on the underside of the structure. The computer codes EQ3NR/EQ6 predict that rainwater flowing through a structure will oxidise iron sulphides present in aggregate fragments, and precipitate ettringite. They also predict that the residual fluid that emerges from the structure has a pH in the range 12-13. It is this hyper-alkaline fluid that reacts with atmospheric carbon dioxide to produce the calcitic growths

Synthetic aperture guided wave imaging using a mobile sensor platform

This oral session at conference looks at synthetic aperture guided wave imaging using a mobile sensor platfor

Explaining ‘Brexit capital’: uneven development and the austerity state

The precise moment that triggered the EU referendum had its roots in the Europhobia that lurked within the soul of the Conservative Party. It has been deeply perturbing to witness such Europhobia played out in the form of an internal party political melodrama while the scandalous socio-economic fissures that fed the Brexit insurgence appeared to represent a mere side-show. Taking inspiration from recent work on Brexit as a critical conjuncture, this paper examines how part of this insurgence emerged as a ‘revolt of the regions’ led by communities that had endured sustained economic dispossession of public goods and services further exacerbated by the steadfast commitment by Conservative-led governments to a politics of austerity. In then sharpening the focus on to Stoke-on-Trent – baptized ‘Capital of Brexit’ in light of its status as the city with the highest Leave majority – the paper reveals deep-seated political disaffection as people railed against prolonged economic abandonment and social injustice. It further identifies how at the very heart of the Brexit conjuncture was a growing disconnect between citizens and the institutions of government, what amounts to a gradual exhaustion of consent for the neoliberal political economic mainstream. It has also resulted in a highly discordant state that is struggling to balance the process of extricating the UK from the EU with the management of a society that is now more imbalanced than at any time in living memory

Control take-all and gain other benefits of eliminating grass from ley pastures by chemical manipulation

Take-all is the most serious root disease of wheat and barley in Western Australia. The fungus which causes take-all (Gaeumannomyces graminis var tritici) is wide spread throughout the wheatbelt but is most common in the high and medium rainfall regions (400mm to 750mm average annual rainfall, see map). Elsewhere in the wheatbelt the presence of take-all affected cereal plants and the loss of crop yield may go unnoticed unless the roots of cereal plants are examined in detail

High speed sCMOS-based oblique plane microscopy applied to the study of calcium dynamics in cardiac myocytes

blique plane microscopy (OPM) is a form of light sheet microscopy that uses a single high numerical aperture microscope objective for both fluorescence excitation and collection. In this paper, measurements of the relative collection efficiency of OPM are presented. An OPM system incorporating two sCMOS cameras is then introduced that enables single isolated cardiac myocytes to be studied continuously for 22 seconds in two dimensions at 667 frames per second with 960 × 200 pixels and for 30 seconds with 960 × 200 × 20 voxels at 25 volumes per second. In both cases OPM is able to record in two spectral channels, enabling intracellular calcium to be studied via the probe Fluo-4 AM simultaneously with the sarcolemma and transverse tubule network via the membrane dye Cellmask Orange. The OPM system was then applied to determine the spatial origin of spontaneous calcium waves for the first time and to measure the cell transverse tubule structure at their point of origin. Further results are presented to demonstrate that the OPM system can also be used to study calcium spark parameters depending on their relationship to the transverse tubule structure

Effects of salinity and diet on the nutritional physiology and alimentary canal histology of the Rainbow trout

In rainbow trout (Salmo gairdneri Richardson) which had been acclimatized to the experimental salinity and temperature for at least 14 days, food intake was maximal in the intermediate salinities of 13.0 and 28.0 p.p.t. (parts per thousand), less in fresh water and 7.5 p.p.t. and minimal, by a statistically significant margin, in 32.5 p.p.t. sea water. There were marked dat-to-day fluctuations in food intake. Upon abrupt salinity increases of 7.5 or 13.0 p.p.t. , there were decreased in growth rate which were related to decreases in food intake. Recovery of food intake and growth rate to pre-increase levels was complete within 14 days. Absorption efficiency, in terms of total dry matter, total energy, and total nitrogen, was negatively related to salinity. Total nitrogen was absorbed considerably more efficiently than either energy or dry matter. Conversion efficiency (K1 and K2) was estimated, also in terms of dry matter, energy and nitrogen, in trout of the 0+ and 1+ year-groups weighing from 50 to 150g. Between 0.0 and 28.0 p.p.t. , there was little effect of salinity on conversion efficiency. Between 28.0 and 32.5 p.p.t. , however, there was a significant decline in food conversion efficiency. The salinity: conversion efficiency relationship was not significantly influenced by fish weight in the range studied. Dry matter and energy conversion were significantly lower than nitrogen conversion efficiency. Neither food intake nor conversion efficiency was significantly affected by dietary sodium chloride supplements of up to 8.5% of the total ration. Over the range of rations from 4% to 38% of dry weight per week, there was a rectilinear relationship between ration and weight increase (% increase in dry weight per week). From this relationship can be estimated the weight maintenance requirement, and the rate of weight loss during fasting. In the same experiment, conversion efficiency (K¬1) increased from 0.00 at 4% dry weight per week (weight maintenance) to 0.19 at 38%, according to the equation K1 = 0.2115 - 0.7699/x. Live weight loss between days 7 and 48 of fasting could be described by a straight line. Trout maintained in 32.5 p.p.t. sea water showed a significantly greater weight loss than those in salinities of up to 15.00 p.p.t. In the liver and white epaxial muscle, n-hexane-extracted lipids fell significantly during fasting. In the white muscle, there was a corresponding slight increase in water content (except in 32.5 p.p.t. sea water). The volume of the gall bladder contents increased during fasting. In the alimentary canal with its associated adipose deposits, there was a very highly significant correlation between lipid and water content. There was a negative relationship between salinity and the density of distribution of mucus cells in the intestinal and rectal epithelia of acclimatized trout. The luminal cross-sectional area of the intestine and rectum, and the height of the intestinal villi tended to increase with salinity. The alimentary canal showed no evidence of histological degeneration after 48 days of fasting in various salinities

Caesalpinia decapetala extracts as inhibitors of lipid oxidation in beef patties

In this study we investigated the effects of Caesalpinia decapetala (CD) extracts on lipid oxidation in ground beef patties. Plant extracts and butylated hydroxytoluene (BHT) were individually added to patties at both 0.1% and 0.5% (w/w) concentrations. We assessed the antioxidant efficacy of CD by the ferric reducing antioxidant power (FRAP) assay and evaluated their potential as natural antioxidants for meat preservation by thiobarbituric acid reactive substance (TBARS) values, hexanal content, fatty acid composition and color parameters. These were tested periodically during 11 days of refrigerated storage. TBARS levels were significantly lower (p ≤ 0.05) in the samples containing plant extracts or BHT than in the non-treated control. In addition, the beef patties formulated with the selected plant extracts showed significantly (p ≤ 0.05) better color stability than those without antioxidants. These results indicate that edible plant extracts are promising sources of natural antioxidants and can potentially be used as functional preservatives in meat products

Quantifying and improving laser range data when scanning industrial materials

This paper presents the procedure and results of a performance study of a miniature laser range scanner, along with a novel error correction calibration. Critically, the study investigates the accuracy and performance of the ranger sensor when scanning large industrial materials over a range of distances. Additionally, the study investigated the effects of small orientation angle changes of the scanner, in a similar manner to which it would experience when being deployed on a mobile robotic platform. A detailed process of error measurement and visualisation was undertaken on a number of parameters, not limited to traditional range data but also received intensity and amplifier gain. This work highlights that significant range distance errors are introduced when optically laser scanning common industrial materials, such as aluminum and stainless steel. The specular reflective nature of some materials results in large deviation in range data from the true value, with mean RMSE errors as high as 100.12 mm recorded. The correction algorithm was shown to reduce the RMSE error associated with range estimation on a planar aluminium surface from 6.48% to 1.39% of the true distance range