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  • 1
    In: Age and Ageing, 2016, Vol. 45(suppl2), pp.ii13-ii56
    Keywords: Medicine;
    ISSN: 0002-0729
    E-ISSN: 1468-2834
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  • 2
    In: PLoS ONE, 2015, Vol.10(9)
    Description: There is currently a significant need to improve our understanding of the factors that control a number of critical soil processes by integrating physical, chemical and biological measurements on soils at microscopic scales to help produce 3D maps of the related properties. Because of technological limitations, most chemical and biological measurements can be carried out only on exposed soil surfaces or 2-dimensional cuts through soil samples. Methods need to be developed to produce 3D maps of soil properties based on spatial sequences of 2D maps. In this general context, the objective of the research described here was to develop a method to generate 3D maps of soil chemical properties at the microscale by combining 2D SEM-EDX data with 3D X-ray computed tomography images. A statistical approach using the regression tree method and ordinary kriging applied to the residuals was developed and applied to predict the 3D spatial distribution of carbon, silicon, iron, and oxygen at the microscale. The spatial correlation between the X-ray grayscale intensities and the chemical maps made it possible to use a regression-tree model as an initial step to predict the 3D chemical composition. For chemical elements, e.g., iron, that are sparsely distributed in a soil sample, the regression-tree model provides a good prediction, explaining as much as 90% of the variability in some of the data. However, for chemical elements that are more homogenously distributed, such as carbon, silicon, or oxygen, the additional kriging of the regression tree residuals improved significantly the prediction with an increase in the R 2 value from 0.221 to 0.324 for carbon, 0.312 to 0.423 for silicon, and 0.218 to 0.374 for oxygen, respectively. The present research develops for the first time an integrated experimental and theoretical framework, which combines geostatistical methods with imaging techniques to unveil the 3-D chemical structure of soil at very fine scales. The methodology presented in this study can be easily adapted and applied to other types of data such as bacterial or fungal population densities for the 3D characterization of microbial distribution.
    Keywords: Research Article
    E-ISSN: 1932-6203
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  • 3
    Language: English
    In: Journal of Cleaner Production, 20 September 2017, Vol.162, pp.1285-1296
    Description: In this work, experimental and modelling investigations were conducted on biochars pyrolyzed at 350 °C and 600 °C, to determine the effect of pyrolysis temperature, hydrogen peroxide activation and pH on copper and zinc removal, in comparison with commercially available activated carbons. Characterization of biochars was performed by BET surface area, elemental analysis and FTIR spectroscopy. Experiments results demonstrated that biochar pyrolyzed at 600 °C adsorbed both copper and zinc more efficiently than biochar pyrolyzed at 350 °C. Chemical activation by H O increased the removal capacity of biochar pyrolyzed at 350 °C. All investigated biochars showed a stronger affinity for copper retention, with a maximum adsorption capacity of 15.7 mg/g while zinc was 10.4 mg/g. The best adsorption performances were obtained at pH 5 and 6. Langmuir adsorption isotherm described copper adsorption process satisfactorily, while zinc adsorption was better described by Freundlich isotherm.
    Keywords: Biochar ; Metal Adsorption ; Isotherms ; Adsorbent ; Copper ; Zinc ; Engineering
    ISSN: 0959-6526
    E-ISSN: 1879-1786
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  • 4
    Language: English
    In: Plant and Soil, 2016, Vol.408(1), pp.357-368
    Description: Background and Aims Biochar amendment to soil is a promising practice of enhancing productivity of agricultural systems. The positive effects on crop are often attributed to a promotion of beneficial soil microorganisms while suppressing pathogens e.g. This study aims to determine the influence of biochar feedstock on (i) spontaneous and fungi inoculated microbial colonisation of biochar particles and (ii) physical pore space characteristics of native and fungi colonised biochar particles which impact microbial habitat quality. Methods Pyrolytic biochars from mixed woods and Miscanthus were investigated towards spontaneous colonisation by classical microbiological isolation, phylogenetic identification of bacterial and fungal strains, and microbial respiration analysis. Physical pore space characteristics of biochar particles were determined by X-ray [mu]-CT. Subsequent 3D image analysis included porosity, surface area, connectivities, and pore size distribution. Results Microorganisms isolated from Wood biochar were more abundant and proliferated faster than those from the Miscanthus biochar. All isolated bacteria belonged to gram-positive bacteria and were feedstock specific. Respiration analysis revealed higher microbial activity for Wood biochar after water and substrate amendment while basal respiration was on the same low level for both biochars. Differences in porosity and physical surface area were detected only in interaction with biochar-specific colonisation. Miscanthus biochar was shown to have higher connectivity values in surface, volume and transmission than Wood biochars as well as larger pores as observed by pore size distribution. Differences in physical properties between colonised and non-colonised particles were larger in Miscanthus biochar than in Wood biochar. Conclusions Vigorous colonisation was found on Wood biochar compared to Miscanthus biochar. This is contrasted by our findings from physical pore space analysis which suggests better habitat quality in Miscanthus biochar than in Wood biochar. We conclude that (i) the selected feedstocks display large differences in microbial habitat quality as well as physical pore space characteristics and (ii) physical description of biochars alone does not suffice for the reliable prediction of microbial habitat quality and recommend that physical and surface chemical data should be linked for this purpose.
    Keywords: Biochar ; Microbial colonisation ; Pore geometry ; Habitat quality
    ISSN: 0032-079X
    E-ISSN: 1573-5036
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  • 5
    Language: English
    In: Bioresource Technology, May 2015, Vol.183, pp.163-174
    Description: This study underpins quantitative relationships that account for the combined effects that starting biomass and peak pyrolysis temperature have on physico-chemical properties of biochar. Meta-data was assembled from published data of diverse biochar samples ( = 102) to (i) obtain networks of intercorrelated properties and (ii) derive models that predict biochar properties. Assembled correlation networks provide a qualitative overview of the combinations of biochar properties likely to occur in a sample. Generalized Linear Models are constructed to account for situations of varying complexity, including: dependence of biochar properties on single or multiple predictor variables, where dependence on multiple variables can have additive and/or interactive effects; non-linear relation between the response and predictors; and non-Gaussian data distributions. The web-tool implements the derived models to maximize their utility and distribution. Provided examples illustrate the practical use of the networks, models and web-tool to engineer biochars with prescribed properties desirable for hypothetical scenarios.
    Keywords: Physico-Chemical Properties ; Slow-Pyrolysis ; Correlation Networks ; Generalized Linear Models ; Web-Tool ; Agriculture ; Engineering ; Chemistry
    ISSN: 0960-8524
    E-ISSN: 1873-2976
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  • 6
    Language: English
    In: Journal of Theoretical Biology, 2007, Vol.248(1), pp.212-224
    Description: We use a correlated random walk model in two dimensions to simulate the movement of the slug parasitic nematode in homogeneous environments. The model incorporates the observed statistical distributions of turning angle and speed derived from time-lapse studies of individual nematode trails. We identify strong temporal correlations between the turning angles and speed that preclude the case of a simple random walk in which successive steps are independent. These correlated random walks are appropriately modelled using an anomalous diffusion model, more precisely using a fractional sub-diffusion model for which the associated stochastic process is characterised by strong memory effects in the probability density function.
    Keywords: Correlated Random Walk ; Stochastic Process With Memory ; Conditional Probability ; Mean Square Displacement ; Biology
    ISSN: 0022-5193
    E-ISSN: 1095-8541
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  • 7
    Language: English
    In: Journal of Biotechnology, August 20, 2015, Vol.208, p.S24
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jbiotec.2015.06.062 Byline: Habibu Abdu, Andrew Spiers, Simona Hapca, Yusuf Deeni Author Affiliation: School Science Engineering and Technology, University of Abertay, Dundee, UK
    Keywords: Genes – Genetic Aspects ; Anopheles – Genetic Aspects ; Pesticide Resistance – Genetic Aspects
    ISSN: 0168-1656
    Source: Cengage Learning, Inc.
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  • 8
    Language: English
    In: Antonie van Leeuwenhoek, January 2013, Vol.103(1), pp.251-9
    Description: The ability to colonise the surface of liquids has obvious advantages for bacteria and biofilm formation at the meniscus and air-liquid (A-L) interface is common amongst environmental pseudomonads. Bacteria from this genus also colonise raw meat and in this work the ability of these to produce biofilms was assessed. Sixty isolates were recovered from vacuum-packed venison, phenotypically characterised and shown by hierarchical cluster analysis to represent a diverse collection of psychrotrophic spoilt venison-associated pseudomonads. Of these, 12 % were found to produce biofilms limited to the meniscus region of the microcosm walls, 31 % produced attached biofilms with significant extensions across the A-L interface and 45 % produced unattached 'floating' biofilms. A combined statistical analysis of growth, biofilm strength and attachment levels revealed that growth affected strength but not attachment, and that there was a significant relationship between attachment and strength. Some environmental pseudomonads are known to utilise cellulose as a biofilm matrix component and here 28 % of the SVP isolates were found to express cellulose by epifluorescent microscopy. This survey suggests that biofilm formation may be more common in psychrotrophic meat-associated isolates than amongst the wider pseudomonad community from which spoilage bacteria might be recruited. This may reflect a selective advantage of bacterial aggregations such as biofilms in environments subject to high levels of physical disturbance. Aggregations may be more resistant to competition and dehydration stress than individual bacteria, whilst fragments of these aggregations may prove more effective in the colonisation of new habitats.
    Keywords: Biofilms -- Growth & Development ; Meat -- Microbiology ; Pseudomonas -- Isolation & Purification
    ISSN: 00036072
    E-ISSN: 1572-9699
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  • 9
    Language: English
    In: Geoderma, Sept 15, 2011, Vol.164(3-4), p.146(9)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.geoderma.2011.05.018 Byline: Simona M. Hapca, Zi X. Wang, Wilfred Otten, Clare Wilson, Philippe C. Baveye Keywords: X-ray CT; SEM-EDX; Segmentation techniques; Spatial correlation; 3D soil images; 2D chemical maps Abstract: Recent 2-dimensional measurements reveal that soils are chemically very heterogeneous at nanometric and micrometric scales. Direct measurement techniques are still lacking to extend these observations to 3 dimensions. Sequential sectioning of soils, followed by 2-dimensional mapping of chemical elements and geometric interpolation to 3D, appears to be the only available alternative. Unfortunately, sectioning of soil samples suffers from geometric distortions that are difficult to avoid in practise. In this regard, the objective of the research described in this article was to develop a procedure enabling one to locate, in a 3D X-ray microtomographic image of a soil sample, a physical surface that is obtained by sectioning and for which a number of chemical maps are available. This procedure involves three steps: (1) the reconstitution of the physical structure of the soil layer surface, (2) the alignment of the chemical maps with the reconstituted soil surface image, and (3) the 3D alignment of the 2D chemical maps with the internal structure of the soil cube. Visual comparison of the C and Si maps and of the reconstituted CT images of the layer surfaces suggests a good correspondence between them, which is supported by Pearson correlation coefficients of -0.57, -0.58, 0.45, and 0.43 for the different surfaces and elements considered. Relative to the original 3D X-ray CT image of the soil sample, the planes associated with the C and Si maps, respectively, are nearly superposed, which further confirms the validity of the alignment procedure. Article History: Received 16 November 2010; Revised 27 May 2011; Accepted 28 May 2011
    Keywords: Soil Structure -- Analysis ; Soil Structure -- Methods ; Soils -- Analysis ; Soils -- Methods
    ISSN: 0016-7061
    Source: Cengage Learning, Inc.
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  • 10
    Language: English
    In: Journal of Biotechnology, 20 August 2015, Vol.208, pp.S24-S24
    Keywords: Engineering
    ISSN: 0168-1656
    E-ISSN: 1873-4863
    Source: ScienceDirect Journals (Elsevier)
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