| 1. |
- Aaltonen, T., et al.
(författare)
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Combination of Tevatron Searches for the Standard Model Higgs Boson in the W+W- Decay Mode
- 2010
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 104:6, s. 061802-
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Tidskriftsartikel (refereegranskat)abstract
- We combine searches by the CDF and D0 Collaborations for a Higgs boson decaying to W+W-. The data correspond to an integrated total luminosity of 4.8 (CDF) and 5.4 (D0) fb(-1) of p (p) over bar collisions at root s = 1.96 TeV at the Fermilab Tevatron collider. No excess is observed above background expectation, and resulting limits on Higgs boson production exclude a standard model Higgs boson in the mass range 162-166 GeV at the 95% C.L.
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| 2. |
- Kawashima, T., et al.
(författare)
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Examination of fragment ions of polystyrene in TOF-SIMS spectra using MS/MS
- 2014
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Ingår i: Surface and Interface Analysis. - : Wiley. - 0142-2421 .- 1096-9918. ; 46, s. 92-95
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Tidskriftsartikel (refereegranskat)abstract
- In this study, tendencies of ionization and cleavage processes of time-of-flight (TOF)-SIMS were examined using MS/MS, which enables an easy qualitative analysis of organic matters, to clarify the fragment ions showing structures of the organic materials. In this paper, a result of reviewing fragment ions in TOF-SIMS spectra for polystyrene (PS) as the representative material is shown. Samples were measured with collision induced dissociation (CID)-MS/MS of 1200L (Varian Inc., USA) and TOF-SIMS J105 (Ionoptika Ltd, UK) for the examination of fragment ions of the PS in TOF-SIMS spectra. The use of CID MS/MS with a wide range of energy distribution is effective for the study of the ionization and cleavage process of TOF-SIMS. As a result, the fragment ions representing the PS structure were clarified, which is useful for the material definition. The qualitative analysis was also applied to the fragment ions particularly obtained in this examination. It is suggested that the examination of the fragmentation process using MS/MS is useful for the mass spectra analysis of organic materials in TOF-SIMS. Copyright (c) 2014 John Wiley & Sons, Ltd.
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| 3. |
- Yokoyama, Y., et al.
(författare)
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Peptide Fragmentation and Surface Structural Analysis by Means of ToF-SIMS Using Large Cluster Ion Sources
- 2016
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 88:7, s. 3592-3597
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Tidskriftsartikel (refereegranskat)abstract
- Peptide or protein structural analysis is crucial for the evaluation of biochips and biodevices, therefore an analytical technique with the ability to detect and identify protein and peptide species directly from surfaces with high lateral resolution is required. In this report, the efficacy of ToF-SIMS to analyze and identify proteins directly from surfaces is evaluated. Although the physics governing the SIMS bombardment process precludes the ability for researchers to detect intact protein or larger peptides of greater than a few thousand mass unit directly, it is possible to obtain information on the partial structures of peptides or proteins using low energy per atom argon duster ion beams. Large cluster ion beams, such as Ar dusters and C-60 ion beams, produce spectra similar to those generated by tandem MS. The SIMS bombardment process also produces peptide fragment ions not detected by conventional MS/MS techniques. In order to clarify appropriate measurement conditions for peptide structural analysis, peptide fragmentation dependency on the energy of a primary ion beam and ToF-SIMS specific fragment ions are evaluated. It was found that the energy range approximately 6 <= E/n <= 10 eV/atom is most effective for peptide analysis based on peptide fragments and [M + H] ions. We also observed the cleaving of side chain moieties at extremely low-energy E/n <= 4 eV/atom.
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| 4. |
- Fletcher, John S., et al.
(författare)
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Prospect of increasing secondary ion yields in ToF-SIMS using water cluster primary ion beams
- 2014
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Ingår i: Surface and Interface Analysis. - : Wiley. - 0142-2421 .- 1096-9918. ; 46, s. 51-53
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Tidskriftsartikel (refereegranskat)abstract
- Low ionization yields in time of flight secondary ion mass spectrometry (ToF-SIMS) particularly from single cells and tissues are proving to be a significant limitation in allowing this technique to reach its full potential. A number of approaches including embedding the sample in water or spraying water above sample surface has shown great prospective for increasing the ionization yield by a factor of 10 to 100 through proton mediated' reaction. Based on this hypothesis, a water cluster primary ion source has been developed in collaboration with Ionoptika Ltd to generate giant water cluster ions (H2O)(n)(+) (n=1-10000) using a similar supersonic jet expansion methodology as for argon cluster beams. The ion yields of arginine, cholesterol, angiotensin II and a lipid mix have been measured under static and high ion dose conditions using (H2O)(5000)(+), (H2O)(3000)(+), Ar-3000(+) and C-60(+) primary ion beams at 20keV. An enhancement in yields up to a factor of around 4 is observed under water cluster impact, in comparison with C-60(+) at 1x10(11)ions/cm(2) ion dose, whereas this increases by around 10-50 times at high ion dose conditions. Copyright (c) 2014 John Wiley & Sons, Ltd.
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