Analysis of Effect of Chromatic Dispersion for Wavelength Tunable Ultrashort Soliton Pulse Generation

The performance characteristics of generated soliton and anti-Stokes pulses for the wavelength tunable ultrashort soliton pulse generation system are discussed for different fiber dispersion parameters of β₂ and β₃ at the pump wavelength. Numerical analysis showed that the broadband wavelength tunability is improved as both the absolute value of negative β₂ and the value of β₃ are decreased. When β₃ is the usual value, the best performance of broadband continuous wavelength tunability which broadens symmetrically to the pump wavelength is obtained for β₃ of around 蜢2 psβ²/km. The reason for this is that the behaviors of both the generated soliton and anti-Stokes pulses are due to the β₂. Through simulations for different fiber dispersion parameters of β₂ or β₃ we obtained interesting results. When β₃ is negative and the zero dispersion wavelength is set at the longer wavelength side than the pump wavelength, such as around 2 μm, it is possible to convert the generated soliton into new components at the longer wavelength side over 2 μm.     

Effect of Guided Acoustic Wave Brillouin Scattering on Pulsed Squeezing in Optical Fibers with Nonlinearity and Dispersion

Quadrature squeezed light generation with optical pulses in a fiber loop mirror is analyzed through computer simulation. The effect of guided acoustic wave Brillouin scattering (GAWBS) in optical fibers as well as those of nonlinearities and chromatic dispersions are considered for the first time. The relation between the GAWBS noise and the optical pulse width is discussed in detail. It is found that the nearly fundamental soliton pulse is optimum to get the largest squeezing even if the GAWBS noise is effective. The broadened pulses suffer larger degradation of squeezing due to this noise.     

Dual modification of a triple-stranded β-helix nanotube with Ru and Re metal complexes to promote photocatalytic reduction of CO2

We have constructed a robust β-helical nanotube from the component proteins of bacteriophage T4 and modified this nanotube with Ru(II)(bpy)(3) and Re(I)(bpy)(CO)(3)Cl complexes. The photocatalytic system arranged on the tube catalyzes the reduction of CO(2) with higher reactivity than that of the mixture of the monomeric forms.     

Structural changes of silk fibroin membranes induced by immersion in methanol aqueous solutions

Structural changes of native and regenerated silk fibroin membranes were induced by immersion in water-methanol solutions and examined as a function of immersion time and methanol concentration. X-ray diffractometry and infrared spectroscopy data showed that transition from random coil to β-sheet structure occurred favorably when both native and regenerated silk fibroin membranes were immersed in water-methanol solutions, regardless of the different immersion time. Only native silk membrane, treated for 2 min with pure methanol, maintained its original amorphous structure, as demonstrated by differential scanning calorimetric (DSC) curves. The degree of displacement, measured by thermomechanical analysis (TMA), was much greater for regenerated than for native silk fibroin membranes. SDS-PAGE pattern showed that native silk fibroin has a molecular weight of 350, while the regenerated sample is formed by a large number of polypeptides in the range of 200-50 KD. The amount of acidic and basic amino acids decreased slightly in regenerated silk fibroin. Physical properties of silk membranes treated with water-methanol solutions are discussed in terms of membrane structure, treatment conditions, and chemical structure of starting material. © 1994 John Wiley & Sons, Inc.     

Synthesis and electrolytic polymerization of the ethylenedioxy-substituted terthiophene-fullerene dyad

[reaction: see text] Two derivatives of ethylenedioxy-substituted terthiophene-fullerene dyads were newly synthesized as the precursors for polythiophene having fullerene side chains. By electrolytic oxidation of dyad 1, the charm-bracelet type polythiophene, poly-1, was obtained as a purple film, which showed electrochemical activity, electrochromism, and photoelectronic response.     

Thermal resistance of sintered powder-liquid 3He boundary

Heat transfer between normal liquid ³He and sintered powders is investigated in terms of the Landau Fermi liquid theory. It is shown that the coupling between zero sound in ³He and low energy vibrational modes in sinter gives the extra contribution to the heat transfer below about 10mK. Theoretical results are compared with experimental data from 2mK to 100mK.     

Gravity wave radiation from unsteady rotational flow in an f-plane shallow water system

Spontaneous gravity wave radiation from an unsteady rotational flow is investigated numerically in an f-plane shallow water system. Unlike the classical Rossby adjustment problem, where free development of an initially unbalanced state is investigated, we consider development of a barotropically unstable zonal flow which is initially balanced but maintained by zonal mean forcing. Gravity waves are continuously radiated from a nearly balanced rotational flow region even when the Froude number is so small that balance dynamics is thought to be a good approximation for the full system. The source of gravity waves is discussed by analogy with the theory of aero-acoustic sound wave radiation (the Lighthill theory). It is shown that the source regions correspond to regions of strong rotational flow. The gradual change of rotational flow causes gravity wave radiation. We propose an approximation for these strong sources on the assumption that the dominant flow in the jet region is non-divergent rotational flow. In addition, we calculate the zonally symmetric component of gravity waves far from the source regions, solving the Lighthill equation. Using scaling analyses for perturbations, these gravity waves can be calculated with only one approximated source term that is related to the latitudinal gradient of the fluid depth and the latitudinal mass flux. In spite of its simplicity, this approximation not only explains the physical cause of gravity wave radiation, but gives an amount of source close to that obtained by classical approximation derived from vortical motion.