| 1. |
- Asahina, Shunsuke, et al.
(författare)
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Direct observation and analysis of york-shell materials using low-voltage high-resolution scanning electron microscopy : Nanometal-particles encapsulated in metal-oxide, carbon, and polymer
- 2014
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Ingår i: APL Materials. - : AIP Publishing. - 2166-532X. ; 2:11, s. 113317-
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Tidskriftsartikel (refereegranskat)abstract
- Nanometal particles show characteristic features in chemical and physical properties depending on their sizes and shapes. For keeping and further enhancing their features, the particles should be protected from coalescence or degradation. One approach is to encapsulate the nanometal particles inside pores with chemically inert or functional materials, such as carbon, polymer, and metal oxides, which contain mesopores to allow permeation of only chemicals not the nanometal particles. Recently developed low-voltage high-resolution scanning electron microscopy was applied to the study of structural, chemical, and electron state of both nanometal particles and encapsulating materials in york-shell materials of Au@C, Ru/Pt@C, Au@TiO2, and Pt@Polymer. Progresses in the following categories were shown for the york-shell materials: (i) resolution of topographic image contrast by secondary electrons, of atomic-number contrast by back-scattered electrons, and of elemental mapping by X-ray energy dispersive spectroscopy; (ii) sample preparation for observing internal structures; and (iii) X-ray spectroscopy such as soft X-ray emission spectroscopy. Transmission electron microscopy was also used for characterization of Au@C. (C) 2014 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.
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| 2. |
- Ginya, Harumi, et al.
(författare)
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Development of the Handy Bio-Strand and its application to genotyping of OPRM1 (A118G)
- 2007
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Ingår i: Analytical Biochemistry. - : Elsevier BV. - 0003-2697 .- 1096-0309. ; 367:1, s. 79-86
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Tidskriftsartikel (refereegranskat)abstract
- We previously developed a three-dimensional microarray system, the Bio-Strand, which exhibits advantages in automated DNA analysis in combination with our Magtration Technology. In the current study, we have developed a compact system for the Bio-Strand, the Handy Bio-Strand, which consists of several tools for the preparation of Bio-Strand Tip, hybridization, and detection. Using the Handy Bio-Strand, we performed single nucleotide polymorphism (SNP) genotyping of OPRM1 (A118G) by allele-specific oligonucleotide competitive hybridization (ASOCH). DNA fragments containing SNP sites were amplified from genomic DNA by PCR and then were fixed on a microporous nylon thread. Thus, prepared Bio-Strand Tip was hybridized with allele-specific Cy5 probes (<15mer), on which the SNP site was designed to be located in the center. By optimizing the amount of competitors, the selectivity of Cy5 probes increased without a drastic signal decrease. OPRM1 (A118G) genotypes of 23 human genomes prepared from whole blood samples were determined by ASOCH using the Handy Bio-Strand. The results were perfectly consistent with those determined by PCR direct sequencing. ASOCH using the Handy Bio-Strand would be a very simple and reliable method for SNP genotyping for small laboratories and hospitals.
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| 3. |
- Harada, Yoshihisa, et al.
(författare)
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Selective Probing of the OH or OD Stretch Vibration in Liquid Water Using Resonant Inelastic Soft-X-Ray Scattering
- 2013
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 111:19, s. 193001-
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Tidskriftsartikel (refereegranskat)abstract
- High-resolution O 1s resonant inelastic x-ray scattering spectra of liquid H2O, D2O, and HDO, obtained by excitation near the preedge resonance show, in the elastic line region, well-separated multiple vibrational structures corresponding to the internal OH stretch vibration in the ground state of water. The energy of the first-order vibrational excitation is strongly blueshifted with respect to the main band in the infrared or Raman spectra of water, indicating that water molecules with a highly weakened or broken donating hydrogen bond are correlated with the preedge structure in the x-ray absorption spectrum. The vibrational profile of preedge excited HDO water is well fitted with 50% +/- 20% greater OH-stretch contribution compared to OD, which strongly supports a preference for OH being the weakened or broken H-bond in agreement with the well-known picture that D2O makes stronger H-bonds than H2O. Accompanying path-integral molecular dynamics simulations show that this is particularly the case for strongly asymmetrically H-bonded molecules, i.e., those that are selected by preedge excitation.
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| 4. |
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| 5. |
- Morokuma, Tomoki, et al.
(författare)
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OISTER optical and near-infrared monitoring observations of peculiar radio-loud active galactic nucleus SDSSJ110006.07+442144.3
- 2017
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Ingår i: Nippon Tenmon Gakkai obun kenkyu hokoku. - : Oxford University Press (OUP). - 0004-6264. ; 69:5
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Tidskriftsartikel (refereegranskat)abstract
- We present monitoring campaign observations at optical and near-infrared (NIR) wavelengths for a radio-loud active galactic nucleus (AGN) at z = 0.840, SDSSJ110006.07+442144.3 (hereafter, J1100+4421), which was identified during a flare phase in late 2014 February. The campaigns consist of three intensive observing runs from the discovery to 2015 March, mostly within the scheme of the OISTER collaboration. Optical-NIR light curves and simultaneous spectral energy distributions (SEDs) are obtained. Our measurements show the strongest brightening in 2015 March. We found that the optical-NIR SEDs of J1100+4421 show an almost steady shape despite the large and rapid intranight variability. This constant SED shape is confirmed to extend to similar to 5 mu m in the observed frame using the archival WISE data. Given the lack of absorption lines and the steep power-law spectrum of alpha(upsilon) similar to -1.4, where f(v) proportional to v(alpha upsilon), synchrotron radiation by a relativistic jet with no or small contributions from the host galaxy and the accretion disk seemsmost plausible as an optical-NIR emission mechanism. The steep optical-NIR spectral shape and the large amplitude of variability are consistent with this object being a low.peak jet-dominated AGN. In addition, sub-arcsecond resolution optical imaging data taken with Subaru Hyper Suprime-Cam does not show a clear extended component and the spatial scales are significantly smaller than the large extensions detected at radio wavelengths. The optical spectrum of a possible faint companion galaxy does not show any emission lines at the same redshift, and hence a merging hypothesis for this AGN-related activity is not supported by our observations.
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| 6. |
- Nordlund, Dennis, et al.
(författare)
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Probing the Electron Delocalization in Liquid Water and Ice at Attosecond Time Scales
- 2007
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Ingår i: Physical Review Letters. - : American Physical Society. - 1079-7114 .- 0031-9007. ; 99, s. 217406-
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Tidskriftsartikel (refereegranskat)abstract
- We determine electron delocalization rates in liquid water and ice using core-hole decay spectroscopy. The hydrogen-bonded network delocalizes the electrons in less than 500 as. Broken or weak hydrogen bonds—in the liquid or at the surface of ice—provide states where the electron remains localized longer than 20 fs. These asymmetrically bonded water species provide electron traps, acting as a strong precursor channel to the hydrated electron.
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| 7. |
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| 8. |
- Pettersson, Lars Gunnar Moody, 1951-, et al.
(författare)
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The local structure of water from combining diffraction and X-ray spectroscopy
- 2022
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Ingår i: Journal of Non-Crystalline Solids: X. - : Elsevier BV. - 2590-1591. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- We build a large (~3400 structures) library of X-ray absorption (XAS) and X-ray emission (XES) spectra computed at high level, which together with their associated structures form the basis for a Monte Carlo fit to the experimental oxygen‑oxygen pair-distribution, XAS and XES spectra for ambient liquid water. The procedure results in weights giving the relative importance of each structure to reproduce the experimental properties. We show that the information content in the X-ray spectroscopic data is strongly complementary to that of X-ray diffraction, and dependent on specific structures that are still consistent with the diffraction data. We fit simultaneously to the X-ray spectroscopy and diffraction experimental data and obtain weights on each structure that give a structural distribution that is consistent with the three experimental datasets. These weights are applied to structural parameters characterizing the local environment of each structure and result in the emergence of more preferred values of these parameters.
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| 9. |
- Pettersson, Lars G. M., et al.
(författare)
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X-ray emission spectroscopy : a genetic algorithm to disentangle core-hole-induced dynamics
- 2021
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Ingår i: Theoretical Chemistry accounts. - : Springer Science and Business Media LLC. - 1432-881X .- 1432-2234. ; 140:12
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Tidskriftsartikel (refereegranskat)abstract
- A genetic algorithm (GA) is developed and applied to make proper connections of final-state potential-energy surfaces and X-ray emission (XES) cross sections between steps in the time-propagation of H-bonded systems after a core–hole is created. We show that this modification results in significantly improved resolution of spectral features in XES with the semiclassical Kramers–Heisenberg approach which takes into account important interference effects. We demonstrate the effects on a water pentamer model as well as on two 17-molecules water clusters representing, respectively, tetrahedral (D2A2) and asymmetric (D1A1) H-bonding environments. For D2A2, the applied procedure improves significantly the obtained intensities, whereas for D1A1 the effects are smaller due to milder dynamics during the core–hole life-time as only one hydrogen is involved. We reinvestigate XES for liquid ethanol and, by properly disentangling the relevant states in the dense manifold of states using the GA, now resolve the important 3a′′ state as a peak rather than a shoulder. Furthermore, by applying the SpecSwap-RMC procedure, we reweigh the distribution of structures in the sampling of the liquid to fit to experiment and estimate the ratio between the main anti and gauche conformers in the liquid at room temperature. This combination of techniques will be generally applicable to challenging problems in liquid-phase spectroscopy.
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| 10. |
- Puettner, Ralph, et al.
(författare)
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Si 1s(-1), 2s(-1) and 2p(-1) lifetime broadening of SiX4 (X = F, Cl, Br, CH3) molecules : SiF4 anomalous behaviour reassessed
- 2019
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : ROYAL SOC CHEMISTRY. - 1463-9076 .- 1463-9084. ; 21:17, s. 8827-8836
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Tidskriftsartikel (refereegranskat)abstract
- The Si 1s(-1), Si 2s(-1), and Si 2p(-1) photoelectron spectra of the SiX4 molecules with X = F, Cl, Br, CH3 were measured. From these spectra the Si 1s(-1) and Si 2s(-1) lifetime broadenings were determined, revealing a significantly larger value for the Si 2s(-1) core hole of SiF4 than for the same core hole of the other molecules of the sequence. This finding is in line with the results of the Si 2p(-1) core holes of a number of SiX4 molecules, with an exceptionally large broadening for SiF4. For the Si 2s(-1) core hole of SiF4 the difference to the other SiX4 molecules can be explained in terms of Interatomic Coulomb Decay (ICD)-like processes. For the Si 2p(-1) core hole of SiF4 the estimated values for the sum of the Intraatomic Auger Electron Decay (IAED) and ICD-like processes are too small to explain the observed linewidth. However, the results of the given discussion render for SiF4 significant contributions from Electron Transfer Mediated Decay (ETMD)-like processes at least plausible. On the grounds of our results, some more molecular systems in which similar processes can be observed are identified.
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