A Ferromagnetic Resonance Study of Iron Complexes as Biologically Synthesized in Magnetic Bacteria

Watanabe, Satoshi; Akutagawa, Sei-ichi; Sawada, Ken; Iwasa, Takeshi; Shimoyama, Yuhei

doi:10.2320/matertrans.m2009177

Cited by 13 publications

(15 citation statements)

References 24 publications

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“…Intense uniaxial ESR spectral peak is indicative of large number of unpaired electrons as dangling bonds . Spin density has been calculated 4.36 × 10 24 spin/g . High spin density is due to unpaired electrons providing reactive surface sites for water molecule dissociation .…”

Section: Resultsmentioning

confidence: 96%

Significance of interface barrier at electrode of hematite hydroelectric cell for generating ecopower by water splitting

et al. 2019

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Summary Recent increase in energy demand and associated environmental degradation concern has triggered more research towards alternative green energy sources. Eco‐friendly energy in facile way has been generated from abundantly available iron oxides using only few microliters of water without any external energy source. Hydroelectric cell (HEC) compatible to environment benign, low cost oxygen‐deficient mesoporous hematite nanoparticles has been used for splitting water molecules spontaneously to generate green electricity. Hematite nanoparticles have been synthesized by coprecipitation method. Chemidissociated hydroxyl group presence on hematite surface has been confirmed by infrared spectroscopy (IR) and X‐ray photoelectron spectroscopy (XPS). Surface oxygen vacancies in nanostructured hematite have been identified by transmission electron microscopy (TEM), XPS, and photoluminescence (PL) measurement. Hematite‐based HEC delivers 30 mA current with 0.92 V emf using approximately 500 μL water. Maximum off‐load output power 27.6 mW delivered by 4.84 cm2 area hematite‐based HEC is 3.52 times higher than reported 7.84 mW power generated by Li‐magnesium ferrite HEC. Electrochemistry of HEC in different irreversible polarization loss regions has been estimated by applying empirical modeling on V‐I polarization curve revealing the reaction and charge transport mechanism of cell. Tafel slope 22.7 mV has been calculated by modeling of activation polarization overvoltage region of 0.11 V. Low activation polarization indicated easy charge/ion diffusion and faster reaction kinetics of Ag/Zn electrode owing to lesser energy barrier at interface. Dissociated H3O+ ions diffuse through surface via proton hopping, while OH− ions migrate through interconnected defective crystallite boundaries resulting into high output cell current.

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Section: Resultsmentioning

confidence: 96%

Significance of interface barrier at electrode of hematite hydroelectric cell for generating ecopower by water splitting

et al. 2019

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“…We report ferromagnetic resonance (FMR) and coercivity distribution characterizations on collections of uncultivated MTB that produce magnetite, co-produce greigite and magnetite, and only greigite. We show that uncultivated MTB are characterized by a wider range of FMR empirical spectral parameters compared with the five cultured magnetite-producing MTB strains that have been characterized to date [20][21][22]25,26,36,37 . We also show that compared with putative Neogene greigite magnetofossil-bearing sedimentary rocks 16,38 , the coercivity distributions of uncultivated MTB that produce magnetite, magnetite and greigite, or greigite only, are fundamentally left-skewed with a lower median.…”

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confidence: 93%

Magnetic properties of uncultivated magnetotactic bacteria and their contribution to a stratified estuary iron cycle

et al. 2014

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Of the two nanocrystal (magnetosome) compositions biosynthesized by magnetotactic bacteria (MTB), the magnetic properties of magnetite magnetosomes have been extensively studied using widely available cultures, while those of greigite magnetosomes remain poorly known. Here we have collected uncultivated magnetite-and greigite-producing MTB to determine their magnetic coercivity distribution and ferromagnetic resonance (FMR) spectra and to assess the MTB-associated iron flux. We find that compared with magnetite-producing MTB cultures, FMR spectra of uncultivated MTB are characterized by a wider empirical parameter range, thus complicating the use of FMR for fossilized magnetosome (magnetofossil) detection. Furthermore, in stark contrast to putative Neogene greigite magnetofossil records, the coercivity distributions for greigite-producing MTB are fundamentally left-skewed with a lower median. Lastly, a comparison between the MTB-associated iron flux in the investigated estuary and the pyritic-Fe flux in the Black Sea suggests MTB play an important, but heretofore overlooked role in euxinic marine system iron cycle.

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“…in the X-band range [11,27,29,36]. S-band FMR spectroscopy operates with microwave frequencies in the 4 GHz range.…”

Section: Basic Principles and Simulationmentioning

confidence: 99%

“…asymmetry of the absorption spectra) permit a direct way to detect the anisotropy of magnetosome chains [11,[27][28][29][30][31][32]. Mastrogiacomo et al [33] showed that FMR experiments of MTB using microwave frequency of 4 GHz, i.e.…”

Section: Introductionmentioning

confidence: 99%

S-band ferromagnetic resonance spectroscopy and the detection of magnetofossils

Gehring

Kind

Charilaou

et al. 2013

J. R. Soc. Interface.

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We report the use of S-band ferromagnetic resonance (FMR) spectroscopy to compare the anisotropic properties of magnetite particles in chains of cultured intact magnetotactic bacteria (MTB) between 300 and 15 K with those of sediment samples of Holocene age in order to infer the presence of magnetofossils and their preservation in a geological time frame. The spectrum of intact MTB at 300 K exhibits distinct uniaxial anisotropy because of the chain alignment of the cellular magnetite particles and their easy axes. This anisotropy becomes less pronounced upon cooling and below the Verwey transition (T V ) it is nearly vanished mainly owing to the change of direction of the easy axes. In a natural sample, magnetofossils were detected by uniaxial anisotropy traits similar to those obtained from cultured MTB above T V . Our comparative study emphasizes that indispensable information can be obtained from S-band FMR spectra, which offers even a better resolution than X-band FMR for discovering magnetofossils, and this in turn can contribute towards strengthening our relatively sparse database for deciphering the microbial ecology during the Earth's history.

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A Ferromagnetic Resonance Study of Iron Complexes as Biologically Synthesized in Magnetic Bacteria

Cited by 13 publications

References 24 publications

Significance of interface barrier at electrode of hematite hydroelectric cell for generating ecopower by water splitting

Significance of interface barrier at electrode of hematite hydroelectric cell for generating ecopower by water splitting

Magnetic properties of uncultivated magnetotactic bacteria and their contribution to a stratified estuary iron cycle

S-band ferromagnetic resonance spectroscopy and the detection of magnetofossils

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