Search Results

You searched for all publications:

with publication states 'Published (Approved)'

Search Again...

These results only include publications that have been reviewed and processed by Diamond Light Source. To also view papers that have not yet been processed click here.

You can use the folder icon under Actions to collate papers as required. You can then click on View Folder in the left-hand navigation to review and/or download your folder.

Exact matches
Related results

25 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2, 3 [Next/Last]

Instruments / Technical Area	Publication Details	Published
I08-Scanning X-ray Microscopy beamline (SXM)	The interplay between Cs and K in Pseudanabaena catenata; from microbial bloom control strategies to bioremediation options for radioactive waters Kejing Zhang , Lynn Foster , Dawn M. Buchanan , Victoria S. Coker , Jon K. Pittman , Jonathan R. Lloyd Journal Of Hazardous Materials 60 DOI: 10.1016/j.jhazmat.2022.130556 Diamond Proposal Number(s): [26072] Open Access Show Abstract ▼ Abstract: Pseudanabaena dominates cyanobacterial blooms in the First-Generation Magnox Storage Pond (FGMSP) at a UK nuclear site. The fission product Cs is a radiologically significant radionuclide in the pond, and understanding the interactions between Cs and Pseudanabaena spp. is therefore important for determining facility management strategies, as well as improving understanding of microbiological responses to this non-essential chemical analogue of K. This study evaluated the fate of Cs following interactions with Pseudanabaena catenata, a laboratory strain most closely related to that dominating FGMSP blooms. Experiments showed that Cs (1 mM) exposure did not affect the growth of P. catenata, while a high concentration of K (5 mM) caused a significant reduction in cell yield. Scanning transmission X-ray microscopy elemental mapping identified Cs accumulation to discrete cytoplasmic locations within P. catenata cells, indicating a potential bioremediation option for Cs. Proteins related to stress responses and nutrient limitation (K, P) were stimulated by Cs treatment. Furthermore, selected K+ transport proteins were mis-regulated by Cs dosing, which indicates the importance of the K+ transport system for Cs accumulation. These findings enhance understanding of Cs fate and biological responses within Pseudanabaena blooms, and indicate that K exposure might provide a microbial bloom control strategy.	Dec 2022
I08-Scanning X-ray Microscopy beamline (SXM)	Investigating nanoscale electron transfer processes at the cell-mineral interface in cobalt-doped ferrihydrite using Geobacter sulfurreducens: a multi-technique approach Dawn M. Buchanan , Laura Newsome , Jonathan R. Lloyd , Majid Kazemian , Burkhard Kaulich , Tohru Araki , Heath Bagshaw , John Waters , Gerrit Van Der Laan , Alpha N’diaye , Victoria S. Coker Frontiers In Earth Science 10 DOI: 10.3389/feart.2022.799328 Diamond Proposal Number(s): [17626] Open Access Show Abstract ▼ Abstract: Cobalt is an essential element for life and plays a crucial role in supporting the drive to clean energy, due to its importance in rechargeable batteries. Co is often associated with Fe in the environment, but the fate of Co in Fe-rich biogeochemically-active environments is poorly understood. To address this, synchrotron-based scanning X-ray microscopy (SXM) was used investigate the behaviour of cobalt at the nanoscale in Co-Fe(III)-oxyhydroxides undergoing microbial reduction. SXM can assess spatial changes in metal speciation and organic compounds helping to elucidate the electron transfer processes occurring at the cell-mineral interface and inform on the fate of cobalt in redox horizons. G. sulfurreducens was used to reduce synthetic Co-ferrihydrite as an analogue of natural cobalt-iron-oxides. Magnetite [Fe(II)/Fe(III)3O4] production was confirmed by powder X-ray diffraction (XRD), SXM and X-ray magnetic circular dichroism (XMCD) data, where best fits of the latter suggested Co-bearing magnetite. Macro-scale XAS techniques suggested Co(III) reduction occurred and complementary SXM at the nanoscale, coupled with imaging, found localised biogenic Co(III) reduction at the cell-mineral interface via direct contact with outer membrane cytochromes. No discernible localised changes in Fe speciation were detected in the reordered cobalt-iron-oxides that were formed and at the end point of the experiment only 11% Co and 1.5% Fe had been solubilised. The solid phase retention, alongside the highly localised and preferential cobalt bioreduction observed at the nanoscale is consistent with retention of Co in redox zones. This work improves our fundamental molecular-scale understanding of the fate of Co in complex environmental systems and supports the development of biogenic Co-doped magnetite for industrial applications from drug delivery systems to magnetic recording media.	May 2022
I06-Nanoscience	Bacterial production of vanadium ferrite spinel (Fe,V)3O4 nanoparticles V. S. Coker , G. Van Der Laan , N. D. Telling , J. R. Lloyd , J. M. Byrne , E. Arenholz , R. A. D. Pattrick Mineralogical Magazine DOI: 10.1180/mgm.2020.55 Diamond Proposal Number(s): [838] Show Abstract ▼ Abstract: Biogenic nanoscale vanadium magnetite is produced by converting V(V)- bearing ferrihydrites through reductive transformation using the metal- reducing bacterium Geobacter sulfurreducens. With increasing vanadium in the ferrihydrite, the amount of V-doped magnetite produced decreased due to V-toxicity which interrupted the reduction pathway ferrihydrite – magnetite, resulting in siderite or goethite formation. Fe L2,3 and V L2,3 X-ray absorption spectra and data from X-ray magnetic circular dichroism analysis revealed the magnetite to contain the V in the Fe(III) Oh site, predominately as V(III) but always with a component of V(VI) present a consistent V(IV)/V(III) ratio in the range 0.28 to 0.33. The bacteriogenic production of V-doped magnetite nanoparticles from V-doped ferrihydrite is confirmed and the work reveals that microbial reduction of contaminant V(V) to V(III)/V(IV) in the environment will occur below the Fe-redox boundary where it will be immobilised in biomagnetite nanoparticles.	Jul 2020
B18-Core EXAFS B22-Multimode InfraRed imaging And Microspectroscopy I06-Nanoscience I10-Beamline for Advanced Dichroism I11-High Resolution Powder Diffraction I12-JEEP: Joint Engineering, Environmental and Processing I18-Microfocus Spectroscopy I22-Small angle scattering & Diffraction	Impact of the Diamond Light Source on research in Earth and environmental sciences: current work and future perspectives I. T. Burke , F. Mosselmans , S. Shaw , C. Peacock , L. G. Benning , V. Coker Philosophical Transactions Of The Royal Society A: Mathematical, Physical And Engineering Sciences 373 (2036), 20130151 - 20130151 DOI: 10.1098/rsta.2013.0151 PMID: 25624516 Open Access Show Abstract ▼ Abstract: Diamond Light Source Ltd celebrated its 10th anniversary as a company in December 2012 and has now accepted user experiments for over 5 years. This paper describes the current facilities available at Diamond and future developments that enhance its capacities with respect to the Earth and environmental sciences. A review of relevant research conducted at Diamond thus far is provided. This highlights how synchrotron-based studies have brought about important advances in our understanding of the fundamental parameters controlling highly complex mineralfluidmicrobe interface reactions in the natural environment. This new knowledge not only enhances our understanding of global biogeochemical processes, but also provides the opportunity for interventions to be designed for environmental remediation and beneficial use.	Jan 2015
I18-Microfocus Spectroscopy	Ex situ formation of metal selenide quantum dots using bacterially derived selenide precursors J. W. Fellowes , R. A. D. Pattrick , J. R. Lloyd , J. M. Charnock , V. S. Coker , J. F. W. Mosselmans , T.-C. Weng , C. I. Pearce Nanotechnology 24 (14) DOI: 10.1088/0957-4484/24/14/145603 PMID: 23508116 Show Abstract ▼ Abstract: Luminescent quantum dots were synthesized using bacterially derived selenide (SeII-) as the precursor. Biogenic SeII- was produced by the reduction of Se-IV by Veillonella atypica and compared directly against borohydride-reduced Se-IV for the production of glutathione-stabilized CdSe and beta-mercaptoethanol-stabilized ZnSe nanoparticles by aqueous synthesis. Biological SeII- formed smaller, narrower size distributed QDs under the same conditions. The growth kinetics of biologically sourced CdSe phases were slower. The proteins isolated from filter sterilized biogenic SeII- included a methylmalonyl-CoA decarboxylase previously characterized in the closely related Veillonella parvula. XAS analysis of the glutathione-capped CdSe at the S K-edge suggested that sulfur from the glutathione was structurally incorporated within the CdSe. A novel synchrotron based XAS technique was also developed to follow the nucleation of biological and inorganic selenide phases, and showed that biogenic SeII- is more stable and more resistant to beam-induced oxidative damage than its inorganic counterpart. The bacterial production of quantum dot precursors offers an alternative, 'green' synthesis technique that negates the requirement of expensive, toxic chemicals and suggests a possible link to the exploitation of selenium contaminated waste streams.	Apr 2013
	Controlled cobalt doping in biogenic magnetite nanoparticles J. M. Byrne , V. S. Coker , S. Moise , P. L. Wincott , D. J. Vaughan , F. Tuna , E. Arenholz , G. Van Der Laan , R. A. D. Pattrick , J. R. Lloyd , N. D. Telling Journal Of The Royal Society Interface 10, 20130134 - 20130134 DOI: 10.1098/rsif.2013.0134 PMID: 23594814 Show Abstract ▼ Abstract: Cobalt-doped magnetite (CoxFe3-xO4) nanoparticles have been produced through the microbial reduction of cobalt-iron oxyhydroxide by the bacterium Geobacter sulfurreducens. The materials produced, as measured by superconducting quantum interference device magnetometry, X-ray magnetic circular dichroism, Mossbauer spectroscopy, etc., show dramatic increases in coercivity with increasing cobalt content without a major decrease in overall saturation magnetization. Structural and magnetization analyses reveal a reduction in particle size to less than 4 nm at the highest Co content, combined with an increase in the effective anisotropy of the magnetic nanoparticles. The potential use of these biogenic nanoparticles in aqueous suspensions for magnetic hyperthermia applications is demonstrated. Further analysis of the distribution of cations within the ferrite spinel indicates that the cobalt is predominantly incorporated in octahedral coordination, achieved by the substitution of Fe2+ site with Co2+, with up to 17 per cent Co substituted into tetrahedral sites.	Mar 2013
	Microbial reduction of arsenic-doped schwertmannite by Geobacter sulfurreducens Richard S. Cutting , Vicky Coker , Neil Telling , Richard L. Kimber , Gerrit Van Der Laan , Richard Pattrick , David J. Vaughan , Elke Arenholz , Jon Lloyd Environmental Science & Technology 46 (22), 12591 - 12599 DOI: 10.1021/es204596z Show Abstract ▼ Abstract: The fate of As(V) during microbial reduction by Geobacter sulfurreducens of Fe(III) in synthetic arsenic-bearing schwertmannites has been investigated. During incubation at pH7, the rate of biological Fe(III) reduction increased with increasing initial arsenic concentration. From schwertmannites with a relatively low arsenic content (<0.3 wt %), only magnetite was formed as a result of dissimilatory iron reduction. However, bioreduction of schwertmannites with higher initial arsenic concentrations (>0.79 wt %) resulted in the formation of goethite. At no stage during the bioreduction process did the concentration of arsenic in solution exceed 120 mu gL(1), even for a schwertmannite with an initial arsenic content of 4.13 wt %. This suggests that the majority of the arsenic is retained in the biominerals or by sorption at the surfaces of newly formed nanoparticles.Subtle differences in the As K-edge XANES spectra obtained from biotransformation products are clearly related to the initial arsenic content of the schwertmannite starting materials. For products obtained from schwertmannites with higher initial As concentrations, one dominant population of As(V) species bonded to only two Fe atoms was evident. By contrast, schwertmannites with relatively low arsenic concentrations gave biotransformation products in which two distinctly different populations of As(V) persisted. The first is the dominant population described above, the second is a minority population characterized by As(V) bonded to four Fe atoms. Both XAS and XMCD evidence suggest that the latter form of arsenic is that taken into the tetrahedral sites of the magnetite.We conclude that the majority population of As(V) is sorbed to the surface of the biotransformation products, whereas the minority population comprises As(V) incorporated into the tetrahedral sites of the biomagnetite. This suggests that microbial reduction of highly bioavailable As(V)-bearing Fe(III) mineral does not necessarily result in the mobilization of the arsenic.	Nov 2012
	Characterisation of the dissimilatory reduction of Fe(III)-oxyhydroxide at the microbe - mineral interface: the application of STXM-XMCD V. S. Coker , J. M. Byrne , N. D. Telling , G. Van Der Laan , J. R. Lloyd , A. P. Hitchcock , J. Wang , R. A. D. Pattrick Geobiology 10 (4), 347-354 DOI: 10.1111/j.1472-4669.2012.00329.x PMID: 22515480 Show Abstract ▼ Abstract: A combination of scanning transmission X-ray microscopy and X-ray magnetic circular dichroism was used to spatially resolve the distribution of different carbon and iron species associated with Shewanella oneidensis MR-1 cells. S. oneidensis MR-1 couples the reduction of Fe(III)-oxyhydroxides to the oxidation of organic matter in order to conserve energy for growth. Several potential mechanisms may be used by S. oneidensis MR-1 to facilitate Fe(III)-reduction. These include direct contact between the cell and mineral surface, secretion of either exogenous electron shuttles or Fe-chelating agents and the production of conductive nanowires. In this study, the protein/lipid signature of the bacterial cells was associated with areas of magnetite (Fe3O4), the product of dissimilatory Fe(III) reduction, which was oversaturated with Fe(II) (compared to stoichiometric magnetite). However, areas of the sample rich in polysaccharides, most likely associated with extracellular polymeric matrix and not in direct contact with the cell surface, were undersaturated with Fe(II), forming maghemite-like (gamma-Fe2O3) phases compared to stoichiometric magnetite. The reduced form of magnetite will be much more effective in environmental remediation such as the immobilisation of toxic metals. These findings suggest a dominant role for surface contact-mediated electron transfer in this study and also the inhomogeneity of magnetite species on the submicron scale present in microbial reactions. This study also illustrates the applicability of this new synchrotron-based technique for high-resolution characterisation of the microbemineral interface, which is pivotal in controlling the chemistry of the Earths critical zone.	Jul 2012
	Engineering biogenic magnetite for sustained Cr(VI) remediation in flow-through systems Daniel E. Crean , Victoria S. Coker , Gerrit Van Der Laan , Jonathan R. Lloyd Environmental Science & Technology 46 (6), 3352-3359 DOI: 10.1021/es2037146 Show Abstract ▼ Abstract: In this work, we report a route to enhance the reactivity and longevity of biogenic magnetite in Cr(VI) remediation under continuous-flow conditions by combining functionalization of the biomagnetite surface with a precious metal catalyst, nanoscale palladium, and exposure to formate. Column influent conditions were varied to simulate oxic, anoxic, and nitrate cocontaminated environments. The addition of sodium formate as an electron donor for Pd-fiinctionalized magnetite increased capacity and longevity allowing 80% removal of Cr(VI) after 300 h in anoxic conditions, whereas complete breakthrough occurred after 60 h in anoxic nonformate and nonfunctionalized systems. Removal of Cr(VI) was optimized under anoxic conditions, and the presence of oxidizing agents results in a modest loss in reductive capacity. Examination of reacted Pd-fiinctionalized magnetite reveals close association of Fe with Cr, suggesting that Pd-coupled oxidation of formate serves to regenerate the reactive surface. XMCD studies revealed that Cr(III) is partially substituted for Fe in the magnetite structure, which serves to immobilize Cr. No evidence for a mechanistic interference by nitrate cocontamination was observed, suggesting that this novel system could provide robust, effective and sustained reduction of contaminants, even in the presence of common oxidizing cocontaminants, outperforming the reductive capacity of nonfunctionalized biogenic magnetite.	Mar 2012
	Control of nanoparticle size, reactivity and magnetic properties during the bioproduction of magnetite by Geobacter sulfurreducens J. M. Byrne , N. D. Telling , V. S. Coker , R. A. D. Pattrick , G. Van Der Laan , E. Arenholz , F. Tuna , J. R. Lloyd Nanotechnology 22 (45) DOI: 10.1088/0957-4484/22/45/455709 Show Abstract ▼ Abstract: The bioproduction of nanoscale magnetite by Fe(III)-reducing bacteria offers a potentially tunable, environmentally benign route to magnetic nanoparticle synthesis. Here, we demonstrate that it is possible to control the size of magnetite nanoparticles produced by Geobacter sulfurreducens by adjusting the total biomass introduced at the start of the process. The particles have a narrow size distribution and can be controlled within the range of 10–50 nm. X-ray diffraction analysis indicates that controlled production of a number of different biominerals is possible via this method including goethite, magnetite and siderite, but their formation is strongly dependent upon the rate of Fe(III) reduction and total concentration and rate of Fe(II) produced by the bacteria during the reduction process. Relative cation distributions within the structure of the nanoparticles have been investigated by x-ray magnetic circular dichroism and indicate the presence of a highly reduced surface layer which is not observed when magnetite is produced through abiotic methods. The enhanced Fe(II)-rich surface, combined with small particle size, has important environmental applications such as in the reductive bioremediation of organics, radionuclides and metals. In the case of Cr(VI), as a model high-valence toxic metal, optimized biogenic magnetite is able to reduce and sequester the toxic hexavalent chromium very efficiently to the less harmful trivalent form.	Nov 2011

Publications Database

Search Results

You searched for all publications:

Search Again...

Subject Areas (check all that apply) select all

Instruments used to collect data (check all that apply) select all

Collaborations involved (check all that apply) select all

Diamond Offline Facilities used

Relevant Technical Areas (check all that apply) select all

Menu for Anonymous User