Chemical Mapping of Polymer Microstructure Using Soft X-ray Spectromicroscopy

Hitchcock, Adam P.; Stöver, Harald D. H.; Croll, Lisa M.; Childs, Ronald F.

doi:10.1071/ch05054

Cited by 33 publications

(27 citation statements)

References 36 publications

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“…More information is available about microorganisms in lake sediments (Benzerara et al, 2005(Benzerara et al, , 2006, in river water (Hitchcock et al, 2005;Lawrence et al, 2003), or in flooded underground tunnels of mines (Chan et al, 2004).…”

Section: Organic Carbon Chemistry In Soilsmentioning

confidence: 99%

“…Conjugated synchrotron STXM and C 1s-NEXAFS was also widely used as a direct solid-state technique to resolve nanostructures of polymers (Smith et al, 2001) and to fingerprint C in biological materials (Hitchcock et al, 2005;Lerotic et al, 2004), where radiation exposure is controlled to avoid damage to the susceptible C¼O bond (Braun et al, 2005;Rightor et al, 1997). High concentrations of C in uniform polymer-layered samples (Ade and Urquhart, 2002) and black C permit NEXAFS data filtering, thereby improving the signal-to-noise ratio of the images allowing to effectively fingerprint the various C functionalities present in these samples.…”

Section: Resolving Key Questions In Soil Biogeochemistrymentioning

confidence: 99%

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Organic Carbon Chemistry in Soils Observed by Synchrotron-Based Spectroscopy

Lehmann

Solomon

2010

Developments in Soil Science

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Section: Organic Carbon Chemistry In Soilsmentioning

confidence: 99%

Section: Resolving Key Questions In Soil Biogeochemistrymentioning

confidence: 99%

Organic Carbon Chemistry in Soils Observed by Synchrotron-Based Spectroscopy

Lehmann

Solomon

2010

Developments in Soil Science

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“…Data Processing. Using the aXis2000 software package 25 both carbon stacks and uranium maps were converted from transmission data to OD. They were then iteratively aligned to convergence by cross-correlation using the Jacobsen stack analyze algorithm 26 with the highest energy image as a reference.…”

Section: X-ray Absorption Spectroscopy (Xas)mentioning

confidence: 99%

Biogeochemical Controls on the Product of Microbial U(VI) Reduction

Stylo

Alessi

Shao

et al. 2013

Environ. Sci. Technol.

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Biologically mediated immobilization of radionuclides in the subsurface is a promising strategy for the remediation of uranium-contaminated sites. During this process, soluble U(VI) is reduced by indigenous microorganisms to sparingly soluble U(IV). The crystalline U(IV) phase uraninite, or UO 2 , is the preferable end-product of bioremediation due to its relatively high stability and low solubility in comparison to biomass-associated nonuraninite U(IV) species that have been reported in laboratory and under field conditions. The goal of this study was to delineate the geochemical conditions that promote the formation of nonuraninite U(IV) versus uraninite and to decipher the mechanisms of its preferential formation. U(IV) products were prepared under varying geochemical conditions and characterized with X-ray absorption spectroscopy (XAS), scanning transmission X-ray microscopy (STXM), and various wet chemical methods. We report an increasing fraction of nonuraninite U(IV) species with decreasing initial U concentration. Additionally, the presence of several common groundwater solutes (sulfate, silicate, and phosphate) promote the formation of nonuraninite U(IV). Our experiments revealed that the presence of those solutes promotes the formation of bacterial extracellular polymeric substances (EPS) and increases bacterial viability, suggesting that the formation of nonuraninite U(IV) is due to a biological response to solute presence during U(VI) reduction. The results obtained from this laboratory-scale research provide insight into biogeochemical controls on the product(s) of uranium reduction during bioremediation of the subsurface.

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“…[1][2][3]16,17 The spectra of peptides and proteins on polymer surfaces is being examined by photoemission electron microscopy (X-PEEM). 4,18 These techniques compliment more common methods for mapping proteins such as laser scanning microscopy of fluorescent labeling proteins, 19 which has high specificity but limited spatial resolution, and immunoelectron microscopy, which has high spatial resolution but requires a chemically fixed sample.…”

Section: Introductionmentioning

confidence: 99%

Using Intrinsic X-ray Absorption Spectral Differences To Identify and Map Peptides and Proteins

et al. 2007

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The intrinsic variation in the near-edge X-ray absorption fine structure (NEXAFS) spectra of peptides and proteins provide an opportunity to identify and map them in various biological environments, without additional labeling. In principle, with sufficiently accurate spectra, peptides (<50 amino acids) or proteins with unusual sequences (e.g., cysteine-or methionine-rich) should be differentiable from other proteins, since the NEXAFS spectrum of each amino acid is distinct. To evaluate the potential for this approach, we have developed X-SpecSim, a tool for quantitatively predicting the C, N, and O 1s NEXAFS spectra of peptides and proteins from their sequences. Here we present the methodology for predicting such spectra, along with tests of its precision using comparisons to the spectra of various proteins and peptides. The C 1s, N 1s, and O 1s spectra of two novel antimicrobial peptides, Indolicidin (ILPWKWPWWPWRR-NH 2 ) and Sub6 (RWWKIWVIR-WWR-NH 2 ), as well as human serum albumin and fibrinogen are reported and interpreted. The ability to identify, differentiate, and quantitatively map an antimicrobial peptide against a background of protein is demonstrated by a scanning transmission X-ray microscopy study of a mixture of albumin and sub6.

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Chemical Mapping of Polymer Microstructure Using Soft X-ray Spectromicroscopy

Cited by 33 publications

References 36 publications

Organic Carbon Chemistry in Soils Observed by Synchrotron-Based Spectroscopy

Organic Carbon Chemistry in Soils Observed by Synchrotron-Based Spectroscopy

Biogeochemical Controls on the Product of Microbial U(VI) Reduction

Using Intrinsic X-ray Absorption Spectral Differences To Identify and Map Peptides and Proteins

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