Continuous dependence results for a general model of size-dependent population dynamics

We are concerned with a general model of size structured population dynamics with the growth rate depending on the individual's size and time. In this paper, we shall study the continuous dependence of the solution on all given data such as aging and birth functions, growth rate functions and initial data.     

Second-order Raman spectra of CsCl single crystals

The second-order Raman spectra of CsCl single crystals have been measured at room temperature for different Raman polarizations and crystal orientations. With the help of the calculated selection rules for a CsCl-type lattice, observed nineteen peaks and shoulders were assigned by the critical point analysis based on the neutron scattering data. By comparing the observed Raman intensities with the thermally weighted two-phonon density-of-states calculated by using a simple shell model, it has turned out that though the measured spectra are dominantly determined by the two-phonon density-of-states, the effect of the q-dependence of the polarizability cannot entirely be neglected.     

Theoretical prediction of maxima in association constants for complex formation between flavin mononucleotide and indoleacetate in the presence of polyelectrolytes

The effects of ionene polymers (6,3-ionene, 6,6-ionene, 6,8-ionene, and 6,12-ionene) with various charge densities upon association constants K for the complexation between flavin mononucleotide and indoleacetate have been studied. Except for 6,12-ionene, K increases with increasing polymer concentration then passes through a maximum, and declines at high polymer concentrations. The value of the maximum K increases in the order 6,8-ionene > 6,3-ionene > 6,6-ionene. In contrast, 6,12-ionene gives only a monotone increasing curve with increasing polymer concentration. These curves are analyzed using the theory of the partition coefficient proposed in the previous paper. The types of the curves that the theory predicts are classified in greater detail than in the previous paper, and examples are given. © 1993 John Wiley & Sons, Inc.     

Fourier domain optical coherence tomography using optical demultiplexers imaging at 60,000,000 lines/s

We describe high-speed Fourier domain optical coherence tomography (OCT) using optical demultiplexers (ODs) for spectral dispersion. The OD enables separation of a narrow spectral band of 14 GHz (0.11 nm) from a broadband incident light at 256 different frequencies in 25.0 GHz intervals centered at 192.2 THz (1559.8 nm). OCT imaging of 60,000,000 axial scans per second was achieved through parallel signal acquisition using 256 balanced photoreceivers to simultaneously detect all the output signals from the ODs in a Fourier domain OCT system. OCT imaging at a 16 kHz frame rate, 1100 A-lines per frame, 3 mm depth range, and 23 microm resolution was demonstrated using a resonant scanner for lateral scanning.     

Band engineering of silicon for light emission: First-principles approach to the effect of co-doping with nitrogen and fluorine

A Si-based light emitter has long been the final key component for electronic and photonic integrated circuits on Si, because Si has an indirect band gap. Atomistic and electronic structures and energy gains of formation of possible nitrogen (N) and fluorine (F) complexes in Si have been researched from first-principles, in order to engineer the band structure of Si for light emission. The calculated results show that the substitutional nitrogen N_S and bond center fluorine F_BC pair complex has large stabilization energy, and that the pair-complex-doped Si has direct band gap, which is reduced with respect to that of Si. These results lead to the possibilities of doping-based engineering of Si optical properties with introduction of deep-level impurity and charge compensation.     

Formation of periodic layered pattern of tetrahydrofuran clathrate hydrates in porous media

Directional growth of tetrahydrofuran (THF) clathrate hydrates was studied in a mixture of glass beads and a stoichiometric THF-water solution. Results showed that disseminated pore space type hydrates formed in a mixture containing 50-microm beads. However, a pure hydrate layer formed pushing the beads in a mixture containing 2-microm beads (frost heaving of hydrates). As the growth proceeded, new layers were formed repeatedly, leading to the eventual formation of a periodic layered pattern. It was found that as the growth rate increased, both the thickness of a hydrate layer and the interval between the neighboring layers decreased according to power laws. The effects of the applied temperature gradient and the weight ratio of the solution and glass beads were also systematically studied. Further, the possibility of applying our model experiments to the formation of natural methane hydrates was discussed.     

Micro-emulsion synthesis of monodisperse surface stabilized silicon nanocrystals

Silicon nanocrystals with a uniform size distribution were synthesized in inverse micelles using powerful hydride reducing agents. The silicon nanocrystals surfaces were then stabilized with 1-heptene to produce particles with strong blue photoluminescence.