We investigated successfully the uptake of the radionuclides with short half-lives, such as 24Na, 28Mg, 43K and 47Ca, and the effect of stable Ca on their uptake in carrot (Daucas carotacv. U.S. harumakigosun) by the multitracer technique. These radionuclides were produced by a fragmentation reaction of Ti in a 135 MeV/nucleon 12C beam accelerated by the RIKEN Ring Cyclotron. This study shows that these radionuclides in a multitracer can be utilized in environmental research.
Authors:T. Kimura, T. Ozaki, Y. Nakai, K. Takeda, and S. Takagi
The molar excess enthalpies of 1,2- and 1,3-propanediamine+1,2- and 1,3-propanediol have been determined at 298.15 K by using
a twin-microcalorimeter which requires each component liquid 1 to 1.5 cm3 for a series of runs over the whole range of mole fraction. All excess enthalpies are exothermic and large. An equilibrium
constant K1 expressed in terms of mole fractions and standard enthalpy of formation of 1:1 complex have been evaluated by ideal mixtures
of momomeric molecules and their associated complexes.
Authors:T. Ozaki, S. Ambe, S. Enomoto, Y. Minai, and Y. Makide
The effect of ZnCl2 on the uptake of Be, Na, Mn, Co, Zn, Se, Rb, Sr, Rh, Cs and lanthanoids (Ce, Pm, Gd and Lu) by carrot (Daucas carota cv. U.S. harumakigosun) was investigated. Uptake was measured using a multitracer technique which enables to acquire information
about various elements under identical conditions. The amount of uptake of Rb, Cs, Sr, Mn and Co, into roots decreased with
increasing concentration of ZnCl2. On the other hand, little effect was observed for the uptake of Be, Se, Rh and lanthanoids. These results suggest that Rb,
Cs, Sr, Mn and Co competed antagonistically with Zn for the binding sites of carriers in the roots, while there was no influence
on the uptake of the other elements. Uptake of Se was not influenced by Cl added as ZnCl2. It is concluded, therefore, that carrot can distinguish Se from Cl based on the physicochemical differences between these
two anion species.
Authors:S. Ohde, M. Hossain, H. Ozaki, and T. Masuzawa
A simple and non-destructive method has been proposed for the routine determination of uranium by epithermal neutron activation analysis in coral skeletons. Using a cadmium capsule, about 0.1-0.2 g samples were irradiated for 6 hours in the Triga Mark II Reactor. Measurements of -ray (239Np via 239U) were performed with each sample and standard after cooling for about three days. Compared with a non-destructive thermal NAA, the present method was found to improve the sensitivity because it reduced the intense Compton background induced by 24Na. We determined uranium in coral standards within 2% of analytical precision. The data obtained for the carbonate standards are mostly consistent with reported values. The present method could be usefully applied to determine uranium contents in fossil corals from the Funafuti Atoll in the Pacific. The distribution of uranium between seawater and coral skeletons is also discussed in order to understand the environmental media in which the coral grew.
Authors:S. Ohde, A. Ramos, H. Ozaki, H. Sawahata, and T. Okai
Boron in carbonate reference samples was measured by neutron-induced prompt gamma-ray analysis (PGA) using cold and thermal neutron guide beams of the JRR-3M reactor. In order to determine B contents in marine carbonates, the Doppler-broadened -ray peak of 478 keV was used together with the correction of interference from Na-peak of 472 keV. We determined B in coral samples within 3% of analytical precision. The data obtained by the present method are mostly consistent with reported values. Here, we report PGA of B in marine carbonates.
Authors:Hayao Ozaki, J. Loenneke, R. Thiebaud, and T. Abe
Cycle training is widely performed as a major part of any exercise program seeking to improve aerobic capacity and cardiovascular health. However, the effect of cycle training on muscle size and strength gain still requires further insight, even though it is known that professional cyclists display larger muscle size compared to controls. Therefore, the purpose of this review is to discuss the effects of cycle training on muscle size and strength of the lower extremity and the possible mechanisms for increasing muscle size with cycle training. It is plausible that cycle training requires a longer period to significantly increase muscle size compared to typical resistance training due to a much slower hypertrophy rate. Cycle training induces muscle hypertrophy similarly between young and older age groups, while strength gain seems to favor older adults, which suggests that the probability for improving in muscle quality appears to be higher in older adults compared to young adults. For young adults, higher-intensity intermittent cycling may be required to achieve strength gains. It also appears that muscle hypertrophy induced by cycle training results from the positive changes in muscle protein net balance.
Authors:H Ozaki, G Kato, T Nakagata, T Nakamura, K Nakada, T Kitada, S Katamoto, and H Naito
This study aimed to investigate the effects of a gradually decreasing intensity training from that corresponding to maximal anaerobic power (MAnP) to that of near maximal oxygen uptake () (decrescent intensity training) on MAnP, maximal accumulated oxygen deficit (MAOD), and in untrained young men. Seventeen untrained young men were randomly divided into either a training (TR; n = 9) group or a control (CON; n = 8) group. The TR group performed the decrescent intensity training, whereas the CON group did not perform any exercises. The mean training time per session throughout the training period was 275 ± 135 s. There was a Group × Time interaction for both absolute and relative (p < 0.01) values of , MAOD, and MAnP. The TR group had significantly increased values for all variables after the 8-week training program, and the relative values of all variables were significantly higher in the TR group than in the CON group. Muscle thicknesses in the anterior and posterior aspects of the thigh and maximal isokinetic knee extension and flexion strengths improved only in the TR group (p < 0.05). A single-exercise training with gradually decreasing intensity from that corresponding to the MAnP to that of approximately 100% improves MAnP, MAOD, and concurrently, despite the short training time per session.
Authors:T. Ozaki, S. Enomoto, Y. Minai, S. Ambe, F. Ambe, and T. Tominaga
About 70 kinds of fem samples have been analyzed by means of neutron activation analysis in order to deduce characteristics and mechanisms of accumulation of rare earth elements. Accumulator species for scandium and lanthanides have been newly found based on the analysis. Correlations among barium, hafnium, and lanthanides indicate that the fems accumulating barium and hafnium also showed high concentrations of lanthanides. Remarkable accumulation of lanthanides in diversifying genera suggests that lanthanides contribute to making those species diverse.
Authors:Y. Takahashi, Y. Minai, T. Ozaki, S. Ambe, M. Iwamoto, H. Maeda, F. Ambe, and T. Tominaga
The multitracer technique was applied to elucidate of influence of humate formation on adsorption behavior of ultratrace elements. Dissolved fractions of Co, As, Rb, Sr, Y, Zr, Ba, Ce, Eu, Gd, Tb, Yb, Lu, Hf, Re and Pt in contact with kaolinite or silica gel were determined simultaneously either in the presence or absence of humic acid, which was partly adsorbed on the solid. Percentage of dissolved fraction of rare earth elements was identical to that of humic acid, indicating high stability of the rare earth-humate complex. Hydrolysis was the most important factor controlling the behavior of Zr and Hf. Both hydrolysis and humate complexation influenced the adsorption of Co, Sr, Ba and Pt, whereas neither affected the distribution of As, Rb and Re.
Authors:Y. Kusaka, H. Tsuji, Y. Tamari, T. Sagawa, S. Ohmori, S. Imai, and T. Ozaki
A new radiochemical group separation method using APDC reagent in the extraction procedure has been developed. The method
has been applied to the radiochemical separation for activated biological samples and also to the preconcentration technique
for sea water samples. The transition elements are extracted into chloroform phase from the pH 3.0 aqueous phase and only
manganese is subsequently extracted from the pH 7.0 aqueous phase. The validity of the method is demonstrated by analyzing
the NBS standard reference materials. In the specimens preconcentrated from the sea water samples adjusted pH to 5.5, vanadium,
manganese, copper and zinc can be determined.