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Journal of Radioanalytical and Nuclear Chemistry
Authors:
Y Kobayashi
,
M. Kubo
,
Y. Yamada
,
T. Saito
,
H. Ueno
,
H. Ogawa
,
W. Sato
,
K. Yoneda
,
H. Watanabe
,
N. Imai
,
H. Miyoshi
, and
K. Asahi

Abstract  

In-beam Mössbauer spectra of 57Fe, decayed from short-lived 57Mn (T1/2 = 1.45 min) implanted into potassium permanganate, KMnO4, were measured at temperatures between 11 K and 130 K. This is the first application of a secondary RI beam to the study of valence states after nuclear transformation. The in-beam Mössbauer spectra obtained below 90 K could be analyzed with two components, a doublet and a singlet. From the calculations of the molecular orbital wave functions, the singlet is suggested to be substitutional 57Fe atoms for Mn-sites in tetrahedral [MnO4] with an unusually high valence state of Fe8+.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
N. Shigeta
,
H. Matsuoka
,
A. Osa
,
M. Koizumi
,
M. Izumo
,
K. Kobayashi
,
K. Hashimoto
,
T. Sekine
, and
R. Lambrecht

Abstract  

No-Carrier-Added186Re was produced using the186W(p,n)186Re nuclear reaction with 13.6 MeV protons on thick targets of 99.79% isotopically enriched186WO3. The theoretical excitation functions for producing186Re, and possible radionuclidic impurities of182Re,183Re, and184Re were calculated using the ALICE code. Cross-sections of the186W(p,n)186Re reaction were measured up to 20 MeV using the stacked target method with thin foils of natural composition tungsten metal. The experimental and theoretical excitation functions were in good agreement. Targetry used at the TIARA cyclotron, and a radiochemical separation scheme for186Re are described.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
K. Tanoi
,
H. Matsue
,
H. Iikura
,
T. Saito
,
Y. Hayashi
,
Y. Hamada
,
H. Nishiyama
,
N. Kobayashi
, and
T. Nakanishi

Abstract  

We carried out instrumental neutron activation analysis (INAA) as well as k 0-based prompt gamma-ray analysis (k 0-PGA) to measure the amount of the elements in onions and studied whether the onions collected from different sites can be categorized based on the elemental concentration profile. Six elements (Na, Mg, Cl, K, Ca, Mn) and 3 elements (B, S, Cl) were measured by INAA and PGA in the onions grown in two districts, Hokkaido and Saga, in Japan, respectively. After principal component analysis, it was found that Cl was an important element to feature the producing districts of onions.

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Abstract  

Quantitative determination of ppb-order 10B was carried out in a small number of cultured tumor cells by particle tracks by the 10B(n,)7Li reactions using solid state nuclear track detector (SSNTD) for boron neutron capture therapy research. The detection limit of 10B concentration in tumor cells is less than 1·10-3 ppm under our experimental conditions which permits the quantitative determination of 10B in a small number of boronated tumor cells (105/ml = ca. 0.1 mg). Boron quantities in tumor cells determined were well compatible with the tumor cell killing effects of boron neutron capture therapy.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
X. Zhao
,
Y. Itoh
,
Y. Aoyagi
,
T. Sugano
,
K. Hirata
,
Y. Kobayashi
,
T. Ohdaira
,
R. Suzuki
, and
T. Mikado

Abstract  

Positron and positronium annihilation investigations were applied to nanocrystalline silicon (nc-Si) thin films, for the first time. The nc-Si thin films with average grain diameters of 3–5 nm show intense blue luminescence at room temperature. The nanometer-sized Si crystallites formed in amorphous Si (a-Si) matrix give rise to this luminescence. Very highS-parameters up to 0.62 were observed in the as-grown a-Si thin film suggesting positronium formation in the a-Si layer. The average lifetime of the positrons in the a-Si was determined to be about 520 ps. TheS-parameters dropped significantly to 0.53 by crystallization of the thin film at 800 °C for 10 seconds, which was almost the same to the value observed in bulk Si (100) substrate. Further crystallization from 60 seconds to 1 hour showed smaller change in theS-parameters than that from the a-Si to 10 seconds. The large change in theS-parameters due to the annealing might be caused by the formation of Si nanocrystallites in a-Si matrix suggesting that positron is a sensitive probe for structural investigations of the nc-Si materials.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
F. Ambe
,
Y. Ohkubo
,
S. Ambe
,
Y. Kobayashi
,
T. Okada
,
Y. Yanagida
,
J. Nakamura
,
K. Asai
,
Y. Kawase
, and
S. Uehara

Abstract  

The features of time-differential perturbed angular correlation (TDPAC) in studies on local chemical structures around impurity atoms are described in comparison with those of Mössbauer emission spectroscopy with four typical examples of recent applications to metal oxide systems, namely,99Rh 99Ru in -Fe2O3 and YBa2Cu3O7– and117Cd 117In in MO (M=Mn, Co, Ni) and BaRu2/3Cd1/3O3.

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Journal of Thermal Analysis and Calorimetry
Authors:
M. Wang
,
Y. Sawada
,
K. Saito
,
S. Horie
,
T. Uchida
,
M. Ohtsuka
,
S. Seki
,
S. Kobayashi
,
T. Arii
,
A. Kishi
,
T. Takahashi
,
Y. Nishimoto
,
T. Wakimoto
,
K. Monzen
,
I. Kashima
,
T. Nishikiori
,
L. Sun
, and
R. Ozao

Abstract  

The thermal change of the tris(8-hydroxyquinolinato)aluminum (Alq3) is currently investigated by XRD-DSC and TG. The phase transition of Alq3 from α-phase to γ-phase takes place at 643–669 K. A very sharp peak with the peak temperature at approx. 709 K is ascribed to the melting of the Alq3. The decomposition of the Alq3 was observed accompanied with the melting and evaporation at >703K. The effect of the atmospheres on the mass loss procedure was studied by TG. It was found that thermal process of Alq3 was strongly influenced by the partial pressure of water vapor in the atmosphere instead of oxygen.

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European Journal of Microbiology and Immunology
Authors:
Ignasi Roca
,
Kathya Espinoza
,
Cinthia Irigoin-Lovera
,
Maria Piquet
,
Luciano A. Palomino-Kobayashi
,
Angie K. Castillo
,
Diego D. Gonzales-DelCarpio
,
Joaquim Viñes
,
Laura Muñoz
,
Barbara Ymaña
,
Rosario Oporto
,
Carlos Zavalaga
,
Maria J. Pons
, and
Joaquim Ruiz

Abstract

Acinetobacter spp. are often isolated from natural sources, but knowledge about their presence in wild animals is fragmented and uncomplete. The present study aimed to characterize a series of Acinetobacter radioresistens isolated from Humboldt penguins (Spheniscus humboldti). Fifteen Humboldt penguins from an inhabited northern Peruvian island were sampled. Microorganisms were identified by MALDI-TOF MS. Antibiotic susceptibility to 12 antimicrobial agents was established, and clonal relationships were determined. A representative isolate was selected for whole genome sequencing (WGS). A. radioresistens were isolated from the feces of 12 (80%) Humboldt penguins, being susceptible to all the antimicrobial agents tested, except eight cefotaxime-intermediate isolates. All A. radioresistens were clonally related. WGS showed that the isolate belonged to ST1972, the presence of two chromosomal encoded carbapenemases (bla OXA-23 and a putative subclass B3 metallo-β-lactamase), and a series of point mutations in antibiotic-resistance related chromosomal genes, which were considered as polymorphisms. In addition, a few virulence factors, including a capsule-encoding operon, superoxide dismutases, catalases, phospholipases and a siderophore receptor were identified. The present results suggest that A. radioresistens may be a common member of the gut microbiota of Humboldt penguins, but further studies in other geographical areas are needed to establish this finding.

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