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Guanglin Yu, Yan Rou Yap, Kathryn Pollock, Allison Hubel
Raman microspectroscopy was used to quantify freezing response of cells to various cooling rates and solution compositions. The distribution pattern of cytochrome c in individual cells was used as a measure of cell viability in the frozen state and this metric agreed well with the population-averaged viability and trypan blue staining experiments. Raman imaging of cells demonstrated that intracellular ice formation (IIF) was common and did not necessarily result in cell death. The amount of intracellular ice as well as ice crystal size played a role in determining whether or not ice inside the cell was a lethal event...
June 20, 2017: Biophysical Journal
Alison B Altman, C Das Pemmaraju, Selim Alayoglu, John Arnold, Corwin H Booth, Augustin Braun, Christopher E Bunker, Alexandre Herve, Stefan G Minasian, David Prendergast, David K Shuh, Tolek Tyliszczak
Oxygen and aluminum K-edge X-ray absorption spectroscopy (XAS), imaging from a scanning transmission X-ray microscope (STXM), and first-principles calculations were used to probe the composition and morphology of bulk aluminum metal, α- and γ-Al2O3, and several types of aluminum nanoparticles. The imaging results agreed with earlier transmission electron microscopy studies that showed a 2 to 5 nm thick layer of Al2O3 on all the Al surfaces. Spectral interpretations were guided by examination of the calculated transition energies, which agreed well with the spectroscopic measurements...
May 4, 2017: Inorganic Chemistry
Satoshi Matsuyama, Shuhei Yasuda, Jumpei Yamada, Hiromi Okada, Yoshiki Kohmura, Makina Yabashi, Tetsuya Ishikawa, Kazuto Yamauchi
X-ray spectromicroscopy with a full-field imaging technique is a powerful method for chemical analysis of heterogeneous complex materials with a nano-scale spatial resolution. For imaging optics, an X-ray reflective optical system has excellent capabilities with highly efficient, achromatic, and long-working-distance properties. An advanced Kirkpatrick-Baez geometry that combines four independent mirrors with elliptic and hyperbolic shapes in both horizontal and vertical directions was developed for this purpose, although the complexity of the system has a limited applicable range...
April 13, 2017: Scientific Reports
Xiaying Xin, Guohe Huang, Xia Liu, Chunjiang An, Yao Yao, Harold Weger, Peng Zhang, Xiujuan Chen
Although pharmaceuticals and personal care products have been used and introduced into the environment in large quantities, little information on potential ecological risks is currently available considering their effects on living organisms. We verified the feasibility of using synchrotron-based Fourier Transform Infrared (SR-FTIR) spectromicroscopy to explore in vivo toxic effects on single living Chlorococcum sp. cells. The study provided important information to achieve a better understanding of the toxic mechanism of triclosan and carbamazepine on living algae Chlorococcum sp...
April 8, 2017: Environmental Pollution
Jonathan D West, Yujie Zhu, Sokunthearath Saem, Jose Moran-Mirabal, Adam P Hitchcock
The C 1s, O 1s, and N 1s X-ray absorption spectra of three lipid species, 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC), and 1,2-dioleoyl-3-trimethylammonium-propane (chloride salt) (DOTAP), have been recorded using transmission detection in a scanning transmission X-ray microscope. The spectra are presented on an absolute intensity scale (i.e., optical density per nm) to allow their use as reference standards for spectromicroscopic analysis of supported lipid bilayers...
May 4, 2017: Journal of Physical Chemistry. B
Daniel M Gottlob, Eugénie Martinez, Claire Mathieu, Christophe Lubin, Nicolas Chevalier, Munique Kazar Mendes, Christelle Charpin, Eric Jalaguier, Olivier Renault, Nicholas Barrett
HfO2-based resistive oxide memories are studied by core-level spectromicroscopy using a laboratory-based X-ray photoelectron emission microscope (XPEEM). After forming, the top electrode is thinned to about 1 nm for the XPEEM analysis, making the buried electrode/HfO2 interface accessible whilst preserving it from contamination. The results are obtained in the true photoemission channel mode from individual memory cells (5 × 5 µm) excited by low-flux laboratory X-rays, in contrast to most studies employing the X-ray absorption channel using potentially harmful bright synchrotron X-rays...
March 23, 2017: Ultramicroscopy
Heng Li, Hui-Yu Cheng, Wei-Liang Chen, Yi-Hsin Huang, Chi-Kang Li, Chiao-Yun Chang, Yuh-Renn Wu, Tien-Chang Lu, Yu-Ming Chang
We performed depth-resolved PL and Raman spectral mappings of a GaN-based LED structure grown on a patterned sapphire substrate (PSS). Our results showed that the Raman mapping in the PSS-GaN heterointerface and the PL mapping in the InxGa1-xN/GaN MQWs active layer are spatially correlated. Based on the 3D construction of E2(high) Raman peak intensity and frequency shift, V-shaped pits in the MQWs can be traced down to the dislocations originated in the cone tip area of PSS. Detail analysis of the PL peak distribution further revealed that the indium composition in the MQWs is related to the residual strain propagating from the PSS-GaN heterointerface toward the LED surface...
March 30, 2017: Scientific Reports
Fusheng Sun, Yaqing Li, Xiang Wang, Zhilai Chi, Guanghui Yu
Understanding the binding characteristics of copper (Cu) to different functional groups in soil dissolved organic matter (DOM) is important to explore Cu toxicity, bioavailability and ultimate fate in the environment. However, the methods used to explore such binding characteristics are still limited. Here, two-dimensional correlation spectroscopy (2DCOS) integrated with Fourier transform infrared (FTIR), (29)Si nuclear magnetic resonance (NMR), (27)Al NMR, and synchrotron-radiation-based FTIR spectromicroscopy were used to explore the binding characteristics of Cu to soil DOM as part of a long-term (23 years) fertilization experiment...
April 2017: Environmental Pollution
Hao Zheng, Guang Bian, Guoqing Chang, Hong Lu, Su-Yang Xu, Guangqiang Wang, Tay-Rong Chang, Songtian Zhang, Ilya Belopolski, Nasser Alidoust, Daniel S Sanchez, Fengqi Song, Horng-Tay Jeng, Nan Yao, Arun Bansil, Shuang Jia, Hsin Lin, M Zahid Hasan
We combine quasiparticle interference simulation (theory) and atomic resolution scanning tunneling spectromicroscopy (experiment) to visualize the interference patterns on a type-II Weyl semimetal Mo_{x}W_{1-x}Te_{2} for the first time. Our simulation based on first-principles band topology theoretically reveals the surface electron scattering behavior. We identify the topological Fermi arc states and reveal the scattering properties of the surface states in Mo_{0.66}W_{0.34}Te_{2}. In addition, our result reveals an experimental signature of the topology via the interconnectivity of bulk and surface states, which is essential for understanding the unusual nature of this material...
December 23, 2016: Physical Review Letters
Waiz Karim, Clelia Spreafico, Armin Kleibert, Jens Gobrecht, Joost VandeVondele, Yasin Ekinci, Jeroen A van Bokhoven
Hydrogen spillover is the surface migration of activated hydrogen atoms from a metal catalyst particle, on which they are generated, onto the catalyst support. The phenomenon has been much studied and its occurrence on reducible supports such as titanium oxide is established, yet questions remain about whether hydrogen spillover can take place on nonreducible supports such as aluminium oxide. Here we use the enhanced precision of top-down nanofabrication to prepare controlled and precisely tunable model systems that allow us to quantify the efficiency and spatial extent of hydrogen spillover on both reducible and nonreducible supports...
January 4, 2017: Nature
K Yamamoto, A Klossek, R Flesch, F Rancan, M Weigand, I Bykova, M Bechtel, S Ahlberg, A Vogt, U Blume-Peytavi, P Schrade, S Bachmann, S Hedtrich, M Schäfer-Korting, E Rühl
The penetration of dexamethasone into human skin ex vivo is reported. X-ray microscopy is used for label-free probing of the drug and quantification of the local drug concentration with a spatial resolution reaching 70±5 nm. This is accomplished by selective probing the dexamethasone by X-ray absorption. Varying the penetration time between 10 min and 1000 min provides detailed information on the penetration process. In addition, the stratum corneum has been damaged by tape-stripping in order to determine the importance of this barrier regarding temporally resolved drug penetration profiles...
December 17, 2016: European Journal of Pharmaceutics and Biopharmaceutics
Fusheng Sun, Matthew L Polizzotto, Dongxing Guan, Jun Wu, Qirong Shen, Wei Ran, Boren Wang, Guanghui Yu
Understanding how heavy metals bind and interact in soils is essential for predicting their distributions, reactions and fates in the environment. Here we propose a novel strategy, i.e., combining two-dimensional correlation spectroscopy (2D COS) and synchrotron radiation based spectromicroscopies, for identifying heavy metal binding to functional groups in soils. The results showed that although long-term (23 yrs) organic fertilization treatment caused the accumulation of Cd (over 3 times) in soils when compared to no fertilization and chemical fertilization treatments, it significantly (p<0...
December 12, 2016: Journal of Hazardous Materials
Suhas Kumar, Ziwen Wang, Xiaopeng Huang, Niru Kumari, Noraica Davila, John Paul Strachan, David Vine, A L David Kilcoyne, Yoshio Nishi, R Stanley Williams
Transition-metal-oxide memristors, or resistive random-access memory (RRAM) switches, are under intense development for storage-class memory because of their favorable operating power, endurance, speed, and density. Their commercial deployment critically depends on predictive compact models based on understanding nanoscale physicochemical forces, which remains elusive and controversial owing to the difficulties in directly observing atomic motions during resistive switching, Here, using scanning transmission synchrotron X-ray spectromicroscopy to study in situ switching of hafnium oxide memristors, we directly observed the formation of a localized oxygen-deficiency-derived conductive channel surrounded by a low-conductivity ring of excess oxygen...
December 27, 2016: ACS Nano
Suhas Kumar, Noraica Davila, Ziwen Wang, Xiaopeng Huang, John Paul Strachan, David Vine, A L David Kilcoyne, Yoshio Nishi, R Stanley Williams
We analyzed micrometer-scale titanium-niobium-oxide prototype memristors, which exhibited low write-power (<3 μW) and energy (<200 fJ per bit per μm(2)), low read-power (∼nW), and high endurance (>millions of cycles). To understand their physico-chemical operating mechanisms, we performed in operando synchrotron X-ray transmission nanoscale spectromicroscopy using an ultra-sensitive time-multiplexed technique. We observed only spatially uniform material changes during cell operation, in sharp contrast to the frequently detected formation of a localized conduction channel in transition-metal-oxide memristors...
December 1, 2016: Nanoscale
A Klossek, S Thierbach, F Rancan, A Vogt, U Blume-Peytavi, E Rühl
Advanced Raman techniques, such as stimulated Raman spectroscopy (SRS), have become a valuable tool for investigations of distributions of substances in biological samples. However, these techniques lack spectral information and are therefore highly affected by cross-sensitivities, which are due to blended Raman bands. One typical example is the symmetric CH2 stretching vibration of lipids, which is blended with the more intense Raman band of proteins. We report in this work an approach to reduce such cross-sensitivities by a factor of 8 in human skin samples...
November 15, 2016: European Journal of Pharmaceutics and Biopharmaceutics
Michael Giulbudagian, Fiorenza Rancan, André Klossek, Kenji Yamamoto, Jana Jurisch, Victor Colombo Neto, Petra Schrade, Sebastian Bachmann, Eckart Rühl, Ulrike Blume-Peytavi, Annika Vogt, Marcelo Calderón
In this paper we present a comprehensive study for the ability of thermoresponsive nanogels (tNG) to act as cutaneous penetration enhancers. Given the unique properties of such molecular architectures with regard to their chemical composition and thermoresponsive properties, we propose a particular mode of penetration enhancement mechanism, i.e. hydration of the stratum corneum. Different tNG were fabricated using dendritic polyglycerol as a multifunctional crosslinker and three different kinds of thermoresponsive polymers as linear counterpart: poly(N-isopropylacrylamide) (pNIPAM), p(di(ethylene glycol) methyl ether methacrylate - co - oligo ethylene glycol methacrylate) (DEGMA-co-OEGMA475), and poly(glycidyl methyl ether - co - ethyl glycidyl ether) (tPG)...
December 10, 2016: Journal of Controlled Release: Official Journal of the Controlled Release Society
Paul M Dietrich, Wolfgang E S Unger, Sufal Swaraj
Soft x-ray spectromicroscopy techniques have seen great amount of development in the recent years, and with the development of new diffraction limited synchrotron source, many new nanoscale and mesoscale characterization opportunities of applied materials are foreseen. In this perspective, the authors present some examples that illustrate the capabilities of spectromicroscopy techniques, namely, 2D and 3D spatially resolved chemical quantification, surface and bulk sensitive measurements, and polarization dependent measurements as applied to iron oxide nanoparticulate materials of biological, geological, and other origins...
October 28, 2016: Biointerphases
Alessandra Gianoncelli, George Kourousias, Lucia Merolle, Matteo Altissimo, Anna Bianco
The current status of the TwinMic beamline at Elettra synchrotron light source, that hosts the European twin X-ray microscopy station, is reported. The X-ray source, provided by a short hybrid undulator with source size and divergence intermediate between bending magnets and conventional undulators, is energy-tailored using a collimated plane-grating monochromator. The TwinMic spectromicroscopy experimental station combines scanning and full-field imaging in a single instrument, with contrast modes such as absorption, differential phase, interference and darkfield...
November 1, 2016: Journal of Synchrotron Radiation
Dogan Erbahar, Toma Susi, Xavier Rocquefelte, Carla Bittencourt, Mattia Scardamaglia, Peter Blaha, Peter Guttmann, Georgios Rotas, Nikos Tagmatarchis, Xiaohui Zhu, Adam P Hitchcock, Chris P Ewels
C60 fullerene crystals may serve as important catalysts for interstellar organic chemistry. To explore this possibility, the electronic structures of free-standing powders of C60 and (C59N)2 azafullerenes are characterized using X-ray microscopy with near-edge X-ray adsorption fine structure (NEXAFS) spectroscopy, closely coupled with density functional theory (DFT) calculations. This is supported with X-ray photoelectron spectroscopy (XPS) measurements and associated core-level shift DFT calculations. We compare the oxygen 1s spectra from oxygen impurities in C60 and C59N, and calculate a range of possible oxidized and hydroxylated structures and associated formation barriers...
October 17, 2016: Scientific Reports
Rita Tóth, Roché M Walliser, István Lagzi, Florent Boudoire, Marcel Düggelin, Artur Braun, Catherine E Housecroft, Edwin C Constable
Periodic precipitation processes in gels can result in impressive micro- and nanostructured patterns known as periodic precipitation (or Liesegang bands). Under certain conditions, the silver nitrate-chromium(vi) system exhibits the coexistence of two kinds of Liesegang bands with different frequencies. We now present that the two kinds of bands form independently on different time scales and the pH-dependent chromate(vi)-dichromate(vi) equilibrium controls the formation of the precipitates. We determined the spatial distribution and constitution of the particles in the bands using focused ion beam-scanning electron microscopy (FIB-SEM) and scanning transmission X-ray spectromicroscopy (STXM) measurements...
October 12, 2016: Soft Matter
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