K Hirata

National Metrology Institute of Japan, Tsukuba, Ibaraki, Japan

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Publications (246)571.1 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: In the secondary ion mass spectrometry (SIMS), use of cluster ions has an advantage of producing a high sensitivity of intact large molecular ions over monatomic ions. This paper presents further yield enhancement of the intact biomolecular ions by measuring the secondary ions emitted in the forward direction. Phenylalanine amino acid films deposited on self-supporting thin Si3N4 films were bombarded with 5 MeV C60 ions. Secondary ions emitted in the forward and backward directions were measured. The yield of intact phenylalanine molecular ions emitted in the forward direction is significantly enhanced compared to the backward direction while fragment ions are suppressed. This suggests a large potential of using transmission cluster ion SIMS for the analysis of biological materials.
    Applied Physics Letters 03/2014; 104(11):114103-114103-4. DOI:10.1063/1.4868655 · 3.52 Impact Factor
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    ABSTRACT: We developed time-of-flight (TOF) secondary ion (SI) mass spectrometry that provides informative SI ion mass spectra without needing a sophisticated ion beam pulsing system. In the newly developed spectrometry, energetic large cluster ions with energies of the order of sub MeV or greater are used as primary ions. Because their impacts on the target surface produce high yields of SIs, the resulting SI mass spectra are informative. In addition, the start signals necessary for timing information on primary ion incidence are provided by the detection signals of particles emitted from the rear surface of foil targets upon transmission of the primary ions. This configuration allows us to obtain positive and negative TOF SI mass spectra without pulsing system, which requires precise control of the primary ions to give the spectra with good mass resolution. We also successfully applied the TOF SI mass spectrometry with energetic cluster ion impacts to the chemical structure characterization of organic thin film targets.
    Review of Scientific Instruments 03/2014; 85(3):033107-033107-6. DOI:10.1063/1.4869036 · 1.58 Impact Factor
  • Journal of Surgical Research 02/2014; 186(2):678. DOI:10.1016/j.jss.2013.11.876 · 2.12 Impact Factor
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    ABSTRACT: Energetic cluster ions with energies of the order of sub MeV or greater were applied to time-of-flight (TOF) secondary ion (SI) mass spectrometry. This gave various advantages including enhancement of SIs required for chemical structure characterization and prevention of charging effects in SI mass spectra for organic targets. We report some characteristic features of TOF SI mass spectrometry using energetic cluster ion impact ionization and discuss two future applications of it.
    Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms 11/2013; 314:39-42. DOI:10.1016/j.nimb.2013.05.045 · 1.19 Impact Factor
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    ABSTRACT: This study evaluated the usefulness of asialoglycoprotein receptor scintigraphy with 99mTc-galactosyl human serum albumin (99mTc-GSA scintigraphy) as an early predictor for prognosis of acute liver failure. Forty-eight patients with acute liver failure and without a past history of chronic liver disease were enrolled. Patients were divided into survival and non-survival groups by 28-day mortality. 99mTc-GSA scintigraphy to detect uptake ratio of the heart at 15 minutes to that at three minutes (HH15) and uptake ratio of the liver at 15 minutes to the liver plus the heart at 15 minutes (LHL15), and measurements of serum total bilirubin, hepatocyte growth factor and prothrombin time were performed immediately after the diagnosis of acute liver failure. Areas under the receiver operating characteristic curves were used to compare the prognostic ability of total bilirubin, hepatocyte growth factor, prothrombin time, HH15 ratio, LHL15 ratio and the model for end-stage liver disease score. Clinical characteristics of patients in the survival group (n=20) and in the non-survival group (n=28) were not significantly different. HH15 and LHL15 uptake ratios in the survival group were 0.670 and 0.875, and they were significantly lower and higher than those in the non-survival group, respectively. All patients with LHL15 <0.760 died, and the area under the receiver operating characteristic curve for LHL15 were significantly larger than the areas under the receiver operating characteristic curves of serum variables and model for end-stage liver disease score. In summary, in patients with acute liver failure without chronic liver disease, HH15 and LHL15 of 99mTc-GSA scintigraphy are more useful variables in predicting prognosis than serum variables and model for end-stage liver disease score.
    Anaesthesia and intensive care 07/2013; 41(4):523-528. · 1.47 Impact Factor
  • Pancreatology 11/2012; 12(6):584-585. DOI:10.1016/j.pan.2012.11.283 · 2.50 Impact Factor
  • 10th Annual Meeting of the Japanese-Society-of-Medical-Oncology (JSMO); 10/2012
  • Rozhledy v chirurgii: měsíčník Československé chirurgické společnosti 06/2012; 91(6):340-5.
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    ABSTRACT: We report suitable secondary ion (SI) counting for surface-sensitive chemical analysis of organic compounds using time-of-flight (TOF) SI mass spectroscopy, based on considerably higher emission yields of SIs induced by cluster ion impact ionization. A SI counting system for a TOF SI mass spectrometer was developed using a fast digital storage oscilloscope, which allows us to perform various types of analysis as all the signal pulses constituting TOF SI mass spectra can be recorded digitally in the system. Effects of the SI counting strategy on SI mass spectra were investigated for C(8) and C(60) cluster ion impacts on an organically contaminated silicon wafer and on polytetrafluoroethylene targets by comparing TOF SI mass spectra obtained from the same recorded signals with different SI counting procedures. Our results show that the use of a counting system, which can cope with high SI yields, is necessary for quantitative analysis of SI mass spectra obtained under high SI yield per impact conditions, including the case of cluster ion impacts on organic compounds.
    The Review of scientific instruments 03/2011; 82(3):033101. DOI:10.1063/1.3541799 · 1.58 Impact Factor
  • Journal of Surgical Research 02/2011; 165(2):214-215. DOI:10.1016/j.jss.2010.11.571 · 2.12 Impact Factor
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    ABSTRACT: Emission yields of secondary ions necessary for the identification of poly-tyrosine were compared for incident ion impacts of energetic cluster ions (0.8MeV C8+, 2.4MeV C8+, and 4.0MeV C8+) and swift heavy monoatomic molybdenum ions (4.0MeV Mo+ and 14MeV Mo4+) with similar mass to that of the cluster by time-of-flight secondary ion mass analysis combined with secondary ion electric current measurements. The comparison revealed that (1) secondary ion emission yields per C8+ impact increase with increasing incident energy within the energy range examined, (2) the 4.0MeV C8+ impact provides higher emission yields than the impact of the monoatomic Mo ion with the same incident energy (4.0MeV Mo+), and (3) the 2.4MeV C8+ impact exhibits comparable emission yields to that for the Mo ion impact with higher incident energy (14MeV Mo4+). Energetic cluster ion impacts effectively produce the characteristic secondary ions for poly-tyrosine, which is advantageous for highly sensitive amino acid detection in proteins using time-of-flight secondary ion mass analysis.
    Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms 10/2010; 268(19):2930-2932. DOI:10.1016/j.nimb.2010.05.011 · 1.19 Impact Factor
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    ABSTRACT: SiO(2) glass with Cs clusters was investigated by differential scanning calorimetry (DSC), thermogravimetric differential analysis (TG-DTA), and positron age-momentum-correlation (AMOC) spectroscopy. No significant peaks arising from Cs clusters were observed in TG-DTA and DSC curves, suggesting Cs clusters in smaller amount than the detection limit of thermal analysis. In contrast to that, AMOC spectroscopy showed ortho-positronium (o-Ps) pick-off annihilation influenced by the presence of Cs clusters. The results demonstrate the feasibility of probing an electronic state of small metal clusters loaded into a disordered system by o-Ps.
    Journal of Physics Conference Series 04/2010; 225. DOI:10.1088/1742-6596/225/1/012046
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    ABSTRACT: This paper reports the development of a street performance robot "SOMENOSUKE" which mimics Japanese traditional juggling "KUWAEBACHI". In this performance, an entertainer holds a drumstick in his/her mouth and then balances an object such as a ball or a teapot on it with great concentration. By considering this trick as a kind of visual feedback control by humans, we develop a robot having a rotating arm with a USB camera. To compensate the delay and the low sampling rate in the visual sensing system, we design a feedback controller based on the sampled-data H<sup>∞</sup> control theory. By considering the addition of blocks as the uncertainty, we achieve the robust stabilization. The performance of our robot is illustrated with experimental data.
    Industrial Electronics, 2009. IECON '09. 35th Annual Conference of IEEE; 12/2009
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    ABSTRACT: Positron age–momentum correlation (AMOC) spectroscopy, which can sensitively probe momentum distributions of positrons and positronium (Ps), was conducted for studying the pick-off process of the triplet bound state ortho-Ps (o-Ps) with electrons at the walls of the free volumes in polymers. Influences of different chemical elements forming free volume were investigated. It was found that the momentum distribution of o-Ps pick-off annihilation sensitively depends on the electronic state in the free volumes. The feasibility of the chemical analysis relevant to the free volume in polymers is discussed.
    Radiation Physics and Chemistry 12/2009; DOI:10.1016/j.radphyschem.2009.06.029 · 1.19 Impact Factor
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    ABSTRACT: Time-resolved momentum distributions of positron−electron annihilation photons were investigated for various polymers by means of positron age−momentum correlation (AMOC) spectroscopy. The momentum distribution exclusively associated with orthopositronium (o-Ps) pick-off annihilation is found to be element-specific and can sensitively probe different light atoms such as C, O, F, and Si that constitute the surface of nanometer-sized free volumes. It is demonstrated that the chemical environment around free volumes in polymers for practical use can be probed by positron annihilation AMOC spectroscopy.
    Macromolecules 07/2009; 42(13). DOI:10.1021/ma900462a · 5.93 Impact Factor
  • Journal of Surgical Research 02/2009; 151(2):304-304. DOI:10.1016/j.jss.2008.11.791 · 2.12 Impact Factor
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    ABSTRACT: To investigate the detailed molecular mechanism of mammary carcinogenesis and discover novel therapeutic targets, we previously analysed gene expression profiles of breast cancers. We here report characterization of a significant role of DTL/RAMP (denticleless/RA-regulated nuclear matrix associated protein) in mammary carcinogenesis. Semiquantitative RT-PCR and northern blot analyses confirmed upregulation of DTL/RAMP in the majority of breast cancer cases and all of breast cancer cell lines examined. Immunocytochemical and western blot analyses using anti-DTL/RAMP polyclonal antibody revealed cell-cycle-dependent localization of endogenous DTL/RAMP protein in breast cancer cells; nuclear localization was observed in cells at interphase and the protein was concentrated at the contractile ring in cytokinesis process. The expression level of DTL/RAMP protein became highest at G(1)/S phases, whereas its phosphorylation level was enhanced during mitotic phase. Treatment of breast cancer cells, T47D and HBC4, with small-interfering RNAs against DTL/RAMP effectively suppressed its expression and caused accumulation of G(2)/M cells, resulting in growth inhibition of cancer cells. We further demonstrate the in vitro phosphorylation of DTL/RAMP through an interaction with the mitotic kinase, Aurora kinase-B (AURKB). Interestingly, depletion of AURKB expression with siRNA in breast cancer cells reduced the phosphorylation of DTL/RAMP and decreased the stability of DTL/RAMP protein. These findings imply important roles of DTL/RAMP in growth of breast cancer cells and suggest that DTL/RAMP might be a promising molecular target for treatment of breast cancer.
    Oncogene 07/2008; 27(43):5672-83. DOI:10.1038/onc.2008.186 · 8.56 Impact Factor
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    ABSTRACT: In this paper, we report time-of-flight (TOF) secondary ion mass spectroscopy using primary C60 ions with an energy range from several tens of keV to several hundreds of keV. Application of the spectroscopy to the analysis of a poly(amino acid) film revealed that characteristic peaks, necessary for identification of the amino acid in proteins, show higher intensities for medium energy C60 (120keV C60+ and 540keV C602+) impacts than those for low energy C60 (30keV C60+) impacts. This finding demonstrates that medium energy C60 ion impacts are useful for highly sensitive characterization of amino acids.
    Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms 05/2008; 266(10):2450-2452. DOI:10.1016/j.nimb.2008.03.019 · 1.19 Impact Factor
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    ABSTRACT: Although mutation of APC or CTNNB1 (beta-catenin) is rare in breast cancer, activation of Wnt signalling is nonetheless thought to play an important role in breast tumorigenesis, and epigenetic silencing of Wnt antagonist genes, including the secreted frizzled-related protein (SFRP) and Dickkopf (DKK) families, has been observed in various tumours. In breast cancer, frequent methylation and silencing of SFRP1 was recently documented; however, altered expression of other Wnt antagonist genes is largely unknown. In the present study, we found frequent methylation of SFRP family genes in breast cancer cell lines (SFRP1, 7 out of 11, 64%; SFRP2, 11 out of 11, 100%; SFRP5, 10 out of 11, 91%) and primary breast tumours (SFRP1, 31 out of 78, 40%; SFRP2, 60 out of 78, 77%; SFRP5, 55 out of 78, 71%). We also observed methylation of DKK1, although less frequently, in cell lines (3 out of 11, 27%) and primary tumours (15 out of 78, 19%). Breast cancer cell lines express various Wnt ligands, and overexpression of SFRPs inhibited cancer cell growth. In addition, overexpression of a beta-catenin mutant and depletion of SFRP1 using small interfering RNA synergistically upregulated transcriptional activity of T-cell factor/lymphocyte enhancer factor. Our results confirm the frequent methylation and silencing of Wnt antagonist genes in breast cancer, and suggest that their loss of function contributes to activation of Wnt signalling in breast carcinogenesis.
    British Journal of Cancer 04/2008; 98(6):1147-56. DOI:10.1038/sj.bjc.6604259 · 4.82 Impact Factor
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    ABSTRACT: Positron (e +) and positronium (Ps) annihilation processes in poly-mers are studied by positron age-momentum correlation spectroscopy, which can sensitively probe momentum distributions of e + , p-Ps, and o-Ps. For polyether sulfone and ethylene tetrafluoroethylene copolymer belonging to oxygen-containing polymers (O group) and fluorine-containing polymers (F group), respectively, significant effects of positron trapping by polar el-ement are observed. The Doppler profile of o-Ps pick-off annihilation is strongly influenced by F atoms, giving rise to anomalous broadening. The results are discussed together with our previous data of the S−I 3 correla-tion in order to explore the feasibility of chemical analysis around the free volumes by age-momentum correlation spectroscopy.
    Acta Physica Polonica Series a 01/2008; 113. · 0.60 Impact Factor

Publication Stats

3k Citations
571.10 Total Impact Points

Institutions

  • 2003–2014
    • National Metrology Institute of Japan
      Tsukuba, Ibaraki, Japan
  • 1994–2013
    • Sapporo Medical University
      • • School of Medicine
      • • Division of Surgery II
      • • Department of Anatomy II
      • • Division of Internal Medicine II
      Sapporo, Hokkaidō, Japan
  • 2001–2009
    • National Institute of Advanced Industrial Science and Technology
      • Electronics and Photonics Research Institute
      Tsukuba, Ibaraki, Japan
    • Ajou University
      • Department of Anatomy
      Seoul, Seoul, South Korea
  • 1993–2005
    • Kobe University
      • Department of Internal Medicine
      Kōbe, Hyōgo, Japan
  • 1996–2001
    • Tsukuba Research Institute
      Edo, Tōkyō, Japan
  • 1998
    • Hokkaido University
      • Institute of Immunological Science
      Sapporo, Hokkaidō, Japan