Helmholtz free energy of a multilayer system of highly charged plates immersed in an electrolyte

The Helmholtz free energy of highly charged plates immersed in an electrolyte solution in a finite container is investigated using mean field theory. Exact solutions of the Poisson-Boltzmann equation under Dirichlet and Neumann boundary conditions lead to analytical expressions for the free energies. Adiabatic potentials of the charged plates, which are derived from the free energy, have long-range weak attractive parts and medium-range strong repulsive parts, irrespective of the type of boundary conditions. The repulsion results mainly from the osmotic pressure of the excess ions trapped between the plates by the large surface charges and the attraction arises essentially from an electric pull from the intermediate cloud of excess counterions shared by the plates.     

C80(Ⅰ,Ⅱ) and Sc2@C80(Ⅰ-Ⅲ):Production,Isolation and Spectrometric Studies

C₈₀ has seven structural isomers satisfying the isolated pentagon rule (IPR)^[1],however,only one isomer of C₈₀(D₂) was isolated and studied so far^[2]. In this study, we report the first successful isolation of multi-isomers of C₈₀ and C₈₀-based endohedral metallofullerenes. The new species were characterized by UV-Vis-NIR absorption spectroscopy, soot-extraction method, chromatographic retention time data and ¹³C NMR spectrometry (for C₈₀(Ⅱ)). It is suggested that C₈₀(Ⅱ) has a D_5d symmetry by the ¹³C NMR pattern (3×20; 2×10) and its long retention time in 5PYE column. For the three isomers of Sc₂@C₈₀,isomer Ⅲ has an extremely long retention time which suggests a D5d symmetry. On the contrary, isomer I has a very short retention time in 5PYE columnso it may have the most spherical I_h symmetry. Theoretically, Sc₂@C₈₀(I_h) is expected to have novel super-conductivity property as the A₃C₆₀ (A=K, Rb).     

Effect of Linewidth Enhancement Factor on Doppler Beat Waveform Obtained from a Self-Mixing Laser Diode

The asymmetry and fringe inclination of the sawtooth-like waveform observed in the self-mixing signal obtained from a semiconductor laser with optical feedback enable the direction discrimination of line-of-sight motion of external target surfaces. We investigated the effects of linewidth enhancement factor and feedback strength on the asymmetry and the direction of fringe inclination of the signal by numerical simulations. For the first time, we show that direction of the fringe inclination is determined not only by the direction of the target motion but also by the value of the linewidth enhancement factor.     

Feasibility studies towards future self-sufficient supply of the 99Mo-99mTc isotopes with Japanese accelerators

In order to establish a self-sufficient supply of ^99mTc, we studied feasibilities to produce its parent nucleus, ⁹⁹Mo, using Japanese accelerators. The daughter nucleus, ^99mTc, is indispensable for medical diagnosis. ⁹⁹Mo has so far been imported from abroad, which is separated from fission products generated in nuclear reactors using enriched ²³⁵U fuel. We investigated ^99mTc production possibilities based on the following three scenarios: (1) ⁹⁹Mo production by the (n, 2n) reaction by spallation neutrons at the J-PARC injector, LINAC; (2) ⁹⁹Mo production by the (p, pn) reaction at E_p = 50–80 MeV proton at the RCNP cyclotron; (3) ^99mTc direct production with a 20 MeV proton beam from the PET cyclotron. Among these three scenarios, scenario (1) is for a scheme on a global scale, scenario (2) works in a local area, and both cases take a long time for negotiations. Scenario (3) is attractive because we can use nearly 50 PET cyclotrons in Japan for ^99mTc production. We here consider both the advantages and disadvantages among the three scenarios by taking account of the Japanese accelerator situation.