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https://www.readbyqxmd.com/read/29893584/express-attenuated-total-reflection-fourier-transform-infrared-atr-ft-ir-spectromicroscopy-using-synchrotron-radiation-and-micromachined-si-wafers-for-microfluidic-applications
#1
Tyler Morhart, Stuart Read, Garth Wells, Michael Jacobs, Scott Rosendahl, Sven Achenbach, Ian James Burgess
No abstract text is available yet for this article.
January 1, 2018: Applied Spectroscopy
https://www.readbyqxmd.com/read/29873342/effect-of-uv-radiation-damage-in-air-on-polymer-film-thickness-studied-by-soft-x-ray-spectromicroscopy
#2
Lis G A Melo, Adam P Hitchcock, Darija Susac, Juergen Stumper, Viatcheslav Berejnov
The thicknesses of thin films of polystyrene (PS), poly(methyl methacrylate) (PMMA), and perfluorosulfonic acid (PFSA) were measured by Ultraviolet Spectral Reflectance (UV-SR) and Scanning Transmission X-ray Microscopy (STXM). At high doses, the UV irradiation in air used in the UV-SR method was found to modify the chemical structures of PS and PMMA (but not PFSA), leading to thinning of these polymer films. The chemical changes caused by UV/air radiation damage were characterized by STXM. When UV and X-ray radiation are applied using no-damage conditions, the film thicknesses measured with the two techniques differ by less than 15% for PS and PMMA and less than 5% for PFSA...
June 6, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29782171/bias-dependent-chemical-enhancement-and-non-classical-stark-effect-in-tip-enhanced-raman-spectromicroscopy-of-co-terminated-ag-tips
#3
Rebecca L M Gieseking, Joonhee Lee, Nicholas Tallarida, Vartkess Ara Apkarian, George C Schatz
Tip-enhanced Raman spectromicroscopy (TERS) with CO-terminated plasmonic tips can probe Ångstrom-scale features of molecules on surfaces. The development of this technique requires understanding of how chemical environments affect the CO vibrational frequency and TERS intensity. At the scanning tunneling microscope junction of a CO-terminated Ag tip, we show that rather than the classical vibrational Stark effect, the large bias dependence of the CO frequency shift is due to ground-state charge transfer from the Ag tip into the CO π* orbital softening the C-O bond at more positive biases...
May 21, 2018: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29737931/rux-largely-restores-lungs-in-iraq-pm-exposed-mice-up-regulating-regulatory-t-cells-tregs
#4
David Lin, Jonathan Li, Rabail Razi, Niha Qamar, Laurie Levine, Thomas Zimmerman, Sayyed A Hamidi, Millicent Schmidt, Marc G Golightly, Todd Rueb, Andrea Harrington, Merrill Garnett, Frank Antonawich, Steven McClain, Courtney Cox, Po Hsuan Huang, Anthony M Szema
Background Military personnel post-deployment to Iraq and Afghanistan have noted new-onset respiratory illness. This study's primary objective was to further develop an animal model of Iraq Afghanistan War Lung Injury (IAW-LI) and to test a novel class of anti-injury drug called RuX. Methods Particulate Matter (PM) samples were obtained in Iraq then characterized by spectromicroscopy. C57BL/6 mice underwent orotracheal instillation with PM, followed by drinkable treatment with RuX. Lung histology, inspiratory capacity (FlexiVent), thymic/splenic regulatory T cell (Treg) number, and whole-lung genomics were analyzed...
May 8, 2018: Experimental Lung Research
https://www.readbyqxmd.com/read/29714202/fast-xanes-fluorescence-imaging-using-a-maia-detector
#5
Ulrike Boesenberg, Christopher G Ryan, Robin Kirkham, Andreas Jahn, Anders Madsen, Gareth Moorhead, Gerald Falkenberg, Jan Garrevoet
A new fast X-ray absorption spectroscopy scanning method was recently implemented at the Hard X-ray Microprobe endstation P06, PETRA III, DESY, utilizing a Maia detector. Spectromicroscopy maps were acquired with spectra for X-ray absorption near-edge structure (XANES) acquisition in the sub-second regime. The method combines XANES measurements with raster-scanning of the sample through the focused beam. The order of the scanning sequence of the axes, one beam energy axis and two (or more) spatial axes, is a variable experimental parameter and, depending on it, the dwell at each location can be either single and continuous (if the energy axis is the inner loop) or in shorter discontinuous intervals (if a spatial axis is innermost)...
May 1, 2018: Journal of Synchrotron Radiation
https://www.readbyqxmd.com/read/29688240/nanoscale-synchrotron-x-ray-speciation-of-iron-and-calcium-compounds-in-amyloid-plaque-cores-from-alzheimer-s-disease-subjects
#6
James Everett, Joanna F Collingwood, Vindy Tjendana-Tjhin, Jake Brooks, Frederik Lermyte, Germán Plascencia-Villa, Ian Hands-Portman, Jon Dobson, George Perry, Neil D Telling
Altered metabolism of biometals in the brain is a key feature of Alzheimer's disease, and biometal interactions with amyloid-β are linked to amyloid plaque formation. Iron-rich aggregates, including evidence for the mixed-valence iron oxide magnetite, are associated with amyloid plaques. To test the hypothesis that increased chemical reduction of iron, as observed in vitro in the presence of aggregating amyloid-β, may occur at sites of amyloid plaque formation in the human brain, the nanoscale distribution and physicochemical states of biometals, particularly iron, were characterised in isolated amyloid plaque cores from human Alzheimer's disease cases using synchrotron X-ray spectromicroscopy...
April 24, 2018: Nanoscale
https://www.readbyqxmd.com/read/29666607/exploring-biogeochemistry-and-microbial-diversity-of-extant-microbialites-in-mexico-and-cuba
#7
Patricia M Valdespino-Castillo, Ping Hu, Martín Merino-Ibarra, Luz M López-Gómez, Daniel Cerqueda-García, Roberto González-De Zayas, Teresa Pi-Puig, Julio A Lestayo, Hoi-Ying Holman, Luisa I Falcón
Microbialites are modern analogs of ancient microbial consortia that date as far back as the Archaean Eon. Microbialites have contributed to the geochemical history of our planet through their diverse metabolic capacities that mediate mineral precipitation. These mineral-forming microbial assemblages accumulate major ions, trace elements and biomass from their ambient aquatic environments; their role in the resulting chemical structure of these lithifications needs clarification. We studied the biogeochemistry and microbial structure of microbialites collected from diverse locations in Mexico and in a previously undescribed microbialite in Cuba...
2018: Frontiers in Microbiology
https://www.readbyqxmd.com/read/29558563/rediscovering-ducos-du-hauron-s-color-photography-through-a-review-of-his-three-color-printing-processes-and-synchrotron-microanalysis-of-his-prints
#8
Marine Cotte, Tiphaine Fabris, Juliette Langlois, Ludovic Bellot-Gurlet, Françoise Ploye, Natalie Coural, Clotilde Boust, Jean-Paul Gandolfo, Thomas Galifot, Jean Susini
Louis Ducos du Huron (1837-1920) dedicated his entire life to the elaboration of physical-chemical processes for color photography. This study aimed at highlighting his unique contribution to three-color printing through 1) an in-depth review of the many protocols he published and 2) the synchrotron-based IR and X-ray microanalysis of fragments sampled in three artworks. Ducos du Hauron's method relied on the preparation and assembly of three monochromes (red, blue, yellow). This study brings to light complex multistep recipes based on photochemistry (carbon print), organic, and inorganic chemistry...
March 20, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/29521387/geometrically-defined-spin-structures-in-ultrathin-fe-3-o-4-with-bulk-like-magnetic-properties
#9
Sandra Ruiz-Gómez, Lucas Pérez, Arantzazu Mascaraque, Adrian Quesada, Pilar Prieto, Irene Palacio, Laura Martín-García, Michael Foerster, Lucía Aballe, Juan de la Figuera
We have grown high quality magnetite microcrystals free from antiphase boundaries on Ru(0001) by reactive molecular beam epitaxy, conserving bulk magnetic properties below 20 nm thickness. Magnetization vector maps are obtained by X-ray spectromicroscopy and compared with micromagnetic simulations. The observed domain configurations are dictated purely by shape anisotropy, overcoming the possible influences of (magneto)crystalline anisotropy and defects, thus demonstrating the possibility of designing spin structures in ultrathin, magnetically soft magnetite at will...
March 28, 2018: Nanoscale
https://www.readbyqxmd.com/read/29479614/development-of-small-particle-speciation-for-nuclear-forensics-by-soft-x-ray-scanning-transmission-spectromicroscopy
#10
J I Pacold, A B Altman, K B Knight, K S Holliday, M J Kristo, S G Minasian, T Tyliszczak, C H Booth, D K Shuh
Synchrotron radiation spectromicroscopy provides a combination of submicron spatial resolution and chemical sensitivity that is well-suited to analysis of heterogeneous nuclear materials. The chemical and physical characteristics determined by scanning transmission X-ray microscopy (STXM) are complementary to information obtained from standard radiochemical analysis methods. In addition, microscopic quantities of radioactive material can be characterized rapidly by STXM with minimal sample handling and intrusion, especially in the case of particulate materials...
March 12, 2018: Analyst
https://www.readbyqxmd.com/read/29377676/insights-into-the-toxicity-of-triclosan-to-green-microalga-chlorococcum-sp-using-synchrotron-based-fourier-transform-infrared-spectromicroscopy-biophysiological-analyses-and-roles-of-environmental-factors
#11
Xiaying Xin, Guohe Huang, Chunjiang An, Charley Huang, Harold Weger, Shan Zhao, Yang Zhou, Scott Rosendahl
This study investigated the toxicity of triclosan to the green microalga Chlorococcum sp. under multiple environmental stressors. The interactions between triclosan and environmental stressors were explored through full two-way factorial, synchrotron-based Fourier transform infrared spectromicroscopy and principal component analyses. Phosphorus concentration, pH * phosphorus concentration, and temperature * pH * NaCl concentration were the most statistically significant factors under triclosan exposure. The variation of those factors would have a huge impact on biophysiological performances...
February 20, 2018: Environmental Science & Technology
https://www.readbyqxmd.com/read/29359936/multiplex-infrared-spectroscopy-imaging-for-monitoring-spatially-resolved-redox-chemistry
#12
Lucyano J A Macedo, Frank N Crespilho
IR spectroscopy is an excellent method for understanding surface redox chemistry. However, obtaining sufficient spatial resolution to analyze in situ surface redox reactions is difficult because the aqueous sampling environments provide some challenges for IR spectroscopy. These challenges arise because of the vibrational contribution of water. In this letter, we demonstrate a solution to this problem, where the key development enabling the coupling of spectromicroscopy with electrochemical measurements is a CaF2 /electrolyte/Au sandwich IR-sensitive sample holder that acts as an electrochemical cell...
February 6, 2018: Analytical Chemistry
https://www.readbyqxmd.com/read/29322945/observation-of-layered-antiferromagnetism-in-self-assembled-parallel-nisi-nanowire-arrays-on-si-110-by-spin-polarized-scanning-tunneling-spectromicroscopy
#13
Ie-Hong Hong, Hsin-Zan Hsu
The layered antiferromagnetism of parallel nanowire (NW) arrays self-assembled on Si(110) have been observed at room temperature by direct imaging of both the topographies and magnetic domains using spin-polarized scanning tunneling microscopy/spectroscopy (SP-STM/STS). The topographic STM images reveal that the self-assembled unidirectional and parallel NiSi NWs grow into the Si(110) substrate along the [Formula: see text] direction (i.e. the endotaxial growth) and exhibit multiple-layer growth. The spatially-resolved SP-STS maps show that these parallel NiSi NWs of different heights produce two opposite magnetic domains, depending on the heights of either even or odd layers in the layer stack of the NiSi NWs...
March 2, 2018: Nanotechnology
https://www.readbyqxmd.com/read/29159351/a-quantitative-analysis-of-the-supercontraction-induced-molecular-disorientation-of-major-ampullate-spider-silk
#14
J Dionne, T Lefèvre, P Bilodeau, M Lamarre, M Auger
Spider silks exhibit remarkable properties, among which the so-called supercontraction, a physical phenomenon by which fibers undergo a longitudinal shrinkage and a radial swelling when exposed to water. The process is marked by a significant decrease in chain orientation resulting from plasticisation of the amorphous phase. Despite several studies that determined the Hermans orientation function, more quantitative data are required to be able to describe theoretically the macroscopic water-induced shrinkage from molecular reorganization...
November 29, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29155910/probing-plasma-fluorinated-graphene-via-spectromicroscopy
#15
C Struzzi, M Scardamaglia, N Reckinger, H Sezen, M Amati, L Gregoratti, J-F Colomer, C Ewels, R Snyders, C Bittencourt
Plasma fluorination of graphene is studied using a combination of spectroscopy and microscopy techniques, giving insight into the yield and fluorination mechanism for functionalization of supported graphene with both CF4 and SF6 gas precursors. Ion acceleration during fluorination is used to probe the effect on grafting functionalities. Adatom clustering, which occurs with CF4 plasma treatment, is suppressed when higher kinetic energy is supplied to the ions. During SF6 plasma functionalization, the sulfur atoms tend to bond to bare copper areas instead of affecting the graphene chemistry, except when the kinetic energy of the ions is restricted...
November 29, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29126948/polymerisation-antibacterial-and-bioactivity-properties-of-experimental-orthodontic-adhesives-containing-triclosan-loaded-halloysite-nanotubes
#16
Felipe Weidenbach Degrazia, Bruna Genari, Vicente Castelo Branco Leitune, Rodrigo Alex Arthur, Santiago Arias Luxan, Susana Maria Werner Samuel, Fabrício Mezzomo Collares, Salvatore Sauro
OBJECTIVE: To evaluate the immediate enamel bond strength, in situ degree of conversion and the polymerisation rate of three experimental orthodontic adhesives containing triclosan-loaded halloysite nanotubes. The antibacterial and bioactivity properties of such experimental materials were also assessed. MATERIALS AND METHODS: Three experimental orthodontic adhesives were formulated by incorporating triclosan-loaded halloysite nanotubes (TCN-HNT) at different concentrations (5wt%, 10wt% and 20wt%) into a resin blend (Control)...
February 2018: Journal of Dentistry
https://www.readbyqxmd.com/read/29035310/a-sub-microanalysis-approach-in-chemical-characterisation-of-gold-nanorods-formed-by-a-novel-polymer-immobilised-gold-seeds-base
#17
Majid Kazemian Abyaneh, Tohru Araki, Burkhard Kaulich
Gold nanorods (GNRs) have been fabricated by a novel polymer-immobilised seed mediated method using ultraviolet (UV) photoreduced gold-polymethylmethacrylate (Au-PMMA) nanocomposites as a seed platform and characterised at sub-micron scale regime with synchrotron-based techniques; near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and X-ray fluorescence (XRF) mapping. In this report, it is shown that investigating polymer nanocomposites using combination of XRF mapping and NEXAFS spectromicroscopy can help to see the growth phenomenon from different perspective than conventional characterisation techniques...
October 16, 2017: Nanomaterials
https://www.readbyqxmd.com/read/28980800/tip-enhanced-raman-spectromicroscopy-on-the-angstrom-scale-bare-and-co-terminated-ag-tips
#18
Nicholas Tallarida, Joonhee Lee, Vartkess Ara Apkarian
The tip is key to the successful execution of tip-enhanced Raman scattering (TERS) measurements in the single molecule limit. We show that nanoscopically smooth silver tips, batch produced through field-directed sputter sharpening, reliably attain TERS with enhancement factors that reach 1013 , as measured by the Raman spectra of single CO molecules attached to the tip apex. We validate the bare tips by demonstrating spectromicroscopy with submolecular spatial resolution and underscore that TERS is a near-field effect that does not obey simple selection rules...
November 28, 2017: ACS Nano
https://www.readbyqxmd.com/read/28976729/tip-enhanced-raman-spectromicroscopy-of-co-ii-tetraphenylporphyrin-on-au-111-toward-the-chemists-microscope
#19
Joonhee Lee, Nicholas Tallarida, Xing Chen, Pengchong Liu, Lasse Jensen, Vartkess Ara Apkarian
Atomically terminated and nanoscopically smooth silver tips effectively focus light on the angstrom scale, allowing tip-enhanced Raman spectromicroscopy (TER-sm) with single molecule sensitivity and submolecular spatial resolution. Through measurements carried out on cobalt-tetraphenylporphyrin (CoTPP) adsorbed on Au(111), we highlight peculiarities of vibrational spectromicroscopy with light confined on the angstrom scale. Field-gradient-driven spectra, orientational fingerprinting, and sculpting of local fields by atomic morphology of the junction are elucidated through measurements that range from 2D arrays at room temperature to single molecule manipulations at 5 K...
November 28, 2017: ACS Nano
https://www.readbyqxmd.com/read/28939848/physical-origins-of-current-and-temperature-controlled-negative-differential-resistances-in-nbo-2
#20
Suhas Kumar, Ziwen Wang, Noraica Davila, Niru Kumari, Kate J Norris, Xiaopeng Huang, John Paul Strachan, David Vine, A L David Kilcoyne, Yoshio Nishi, R Stanley Williams
Negative differential resistance behavior in oxide memristors, especially those using NbO2 , is gaining renewed interest because of its potential utility in neuromorphic computing. However, there has been a decade-long controversy over whether the negative differential resistance is caused by a relatively low-temperature non-linear transport mechanism or a high-temperature Mott transition. Resolving this issue will enable consistent and robust predictive modeling of this phenomenon for different applications...
September 22, 2017: Nature Communications
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