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https://www.readbyqxmd.com/read/28774096/in-situ-soft-x-ray-spectromicroscopy-of-early-tricalcium-silicate-hydration
#1
Sungchul Bae, Manabu Kanematsu, Daniel Hernández-Cruz, Juhyuk Moon, David Kilcoyne, Paulo J M Monteiro
The understanding and control of early hydration of tricalcium silicate (C₃S) is of great importance to cement science and concrete technology. However, traditional characterization methods are incapable of providing morphological and spectroscopic information about in situ hydration at the nanoscale. Using soft X-ray spectromicroscopy, we report the changes in morphology and molecular structure of C₃S at an early stage of hydration. In situ C₃S hydration in a wet cell, beginning with induction (~1 h) and acceleration (~4 h) periods of up to ~8 h, was studied and compared with ex situ measurements in the deceleration period after 15 h of curing...
December 1, 2016: Materials
https://www.readbyqxmd.com/read/28772490/effects-of-incorporating-high-volume-fly-ash-into-tricalcium-silicate-on-the-degree-of-silicate-polymerization-and-aluminum-substitution-for-silicon-in-calcium-silicate-hydrate
#2
Sungchul Bae, Rae Taylor, David Kilcoyne, Juhyuk Moon, Paulo J M Monteiro
This study assesses the quantitative effects of incorporating high-volume fly ash (HVFA) into tricalcium silicate (C₃S) paste on the hydration, degree of silicate polymerization, and Al substitution for Si in calcium silicate hydrate (C-S-H). Thermogravimetric analysis and isothermal conduction calorimetry showed that, although the induction period of C₃S hydration was significantly extended, the degree of hydration of C₃S after the deceleration period increased due to HVFA incorporation. Synchrotron-sourced soft X-ray spectromicroscopy further showed that most of the C₃S in the C₃S-HVFA paste was fully hydrated after 28 days of hydration, while that in the pure C₃S paste was not...
February 4, 2017: Materials
https://www.readbyqxmd.com/read/28760619/gamma-irradiated-human-amniotic-membrane-decellularised-with-sodium-dodecyl-sulfate-is-a-more-efficient-substrate-for-the-ex-vivo-expansion-of-limbal-stem-cells
#3
G S Figueiredo, S Bojic, P Rooney, S-P Wilshaw, C J Connon, R M Gouveia, C Paterson, G Lepert, H S Mudhar, F C Figueiredo, M Lako
The gold standard substrate for the ex vivo expansion of human limbal stem cells (LSCs) remains the human amniotic membrane (HAM) but this is not a defined substrate and is subject to biological variability and the potential to transmit disease. To better define HAM and mitigate the risk of disease transmission, we sought to determine if decellularisation and/or γ-irradiation have an adverse effect on culture growth and LSC phenotype. Ex vivo limbal explant cultures were set up on fresh HAM, HAM decellularised with 0...
July 29, 2017: Acta Biomaterialia
https://www.readbyqxmd.com/read/28719608/cholesterol-esterification-inhibition-and-imatinib-treatment-synergistically-inhibit-growth-of-bcr-abl-mutation-independent-resistant-chronic-myelogenous-leukemia
#4
Shovik Bandyopadhyay, Junjie Li, Elie Traer, Jeffrey W Tyner, Amy Zhou, Stephen T Oh, Ji-Xin Cheng
Since the advent of tyrosine kinase inhibitors (TKIs) such as imatinib, nilotinib, and dasatinib, chronic myelogenous leukemia (CML) prognosis has improved greatly. However, ~30-40% of patients develop resistance to imatinib therapy. Although most resistance is caused by mutations in the BCR-ABL kinase domain, 50-85% of these patients develop resistance in the absence of new mutations. In these cases, targeting other pathways may be needed to regain clinical response. Using label-free Raman spectromicroscopy, we evaluated a number of leukemia cell lines and discovered an aberrant accumulation of cholesteryl ester (CE) in CML, which was found to be a result of BCR-ABL kinase activity...
2017: PloS One
https://www.readbyqxmd.com/read/28702656/polarization-landscape-effects-in-soft-x-ray-induced-surface-chemical-decomposition-of-lead-zirco-titanate-evidenced-by-photoelectron-spectromicroscopy
#5
Laura E Abramiuc, Liviu C Tănase, Alexei Barinov, Nicoleta G Apostol, Cristina Chirilă, Lucian Trupină, Lucian Pintilie, Cristian M Teodorescu
The stability of thin films of lead zirco-titanate (PZT) under intense soft X-ray beams is investigated by time-resolved photoelectron spectromicroscopy with a lateral resolution below 1 micrometer. Surface dissociation is observed when samples are irradiated with intense (5 × 10(23) photons per s per m(2)) soft X-rays, with promotion of reduced lead on the surface. On areas exhibiting outwards polarization (P((+))), the reduced lead is formed at the expense of P((+))-PZT. On areas presenting co-existing P((+)) states with areas without out-of-plane polarization (P((0))), the reduced lead is formed at the expense of the P((0))-PZT component, while the P((+))-PZT remains constant...
July 12, 2017: Nanoscale
https://www.readbyqxmd.com/read/28692273/protein-mixture-segregation-at-coffee-ring-real-time-imaging-of-protein-ring-precipitation-by-ftir-spectromicroscopy
#6
Sun Choi, Giovanni Birarda
During natural drying process, all solutions and suspensions tend to form the so-called "coffee-ring" deposits. This phenomenon, by far, has been interpreted by the hydrodynamics of evaporating fluids. However, in this study, by applying Fourier transform infrared imaging (FTIRI), it is possible to observe the segregation and separation of a protein mixture at the "ring", hence we suggest a new way to interpret "coffee-ring effect" of solutions. The results explore the dynamic process that leads to the ring formation in case of model plasma proteins, such as BGG (bovine γ globulin), BSA (bovine serum albumin), and Hfib (human fibrinogen), and also report fascinating discovery of the segregation at the ring deposits of two model proteins BGG and BSA, which can be explained by an energy kinetic model, only...
July 18, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28636921/characterizing-intracellular-ice-formation-of%C3%A2-lymphoblasts-using-low-temperature-raman%C3%A2-spectroscopy
#7
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
https://www.readbyqxmd.com/read/28471186/chemical-and-morphological-inhomogeneity-of-aluminum-metal-and-oxides-from-soft-x-ray-spectromicroscopy
#8
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
https://www.readbyqxmd.com/read/28406227/50-nm-resolution-full-field-x-ray-microscope-without-chromatic-aberration-using-total-reflection-imaging-mirrors
#9
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
https://www.readbyqxmd.com/read/28399502/molecular-toxicity-of-triclosan-and-carbamazepine-to-green-algae-chlorococcum-sp-a-single-cell-view-using-synchrotron-based-fourier-transform-infrared-spectromicroscopy
#10
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...
July 2017: Environmental Pollution
https://www.readbyqxmd.com/read/28398060/x-ray-absorption-spectroscopy-and-spectromicroscopy-of-supported-lipid-bilayers
#11
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
https://www.readbyqxmd.com/read/28390735/laboratory-based-x-ray-photoemission-core-level-spectromicroscopy-of-resistive-oxide-memories
#12
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
https://www.readbyqxmd.com/read/28358119/three-dimensional-characterization-of-gan-based-light-emitting-diode-grown-on-patterned-sapphire-substrate-by-confocal-raman-and-photoluminescence-spectromicroscopy
#13
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
https://www.readbyqxmd.com/read/28118997/using-new-hetero-spectral-two-dimensional-correlation-analyses-and-synchrotron-radiation-based-spectromicroscopy-to-characterize-binding-of-cu-to-soil-dissolved-organic-matter
#14
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
https://www.readbyqxmd.com/read/28059545/atomic-scale-visualization-of-quasiparticle-interference-on-a-type-ii-weyl-semimetal-surface
#15
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
https://www.readbyqxmd.com/read/28054605/catalyst-support-effects-on-hydrogen-spillover
#16
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
https://www.readbyqxmd.com/read/27998691/influence-of-the-skin-barrier-on-the-penetration-of-topically-applied-dexamethasone-probed-by-soft-x-ray-spectromicroscopy
#17
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±5nm. This is accomplished by selective probing the dexamethasone by X-ray absorption. Varying the penetration time between 10min and 1000min 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...
September 2017: European Journal of Pharmaceutics and Biopharmaceutics
https://www.readbyqxmd.com/read/27987446/exploring-the-interactions-and-binding-sites-between-cd-and-functional-groups-in-soil-using-two-dimensional-correlation-spectroscopy-and-synchrotron-radiation-based-spectromicroscopies
#18
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
https://www.readbyqxmd.com/read/27957851/conduction-channel-formation-and-dissolution-due-to-oxygen-thermophoresis-diffusion-in-hafnium-oxide-memristors
#19
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
https://www.readbyqxmd.com/read/27906408/spatially-uniform-resistance-switching-of-low-current-high-endurance-titanium-niobium-oxide-memristors
#20
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
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