Nonlinear waves in the Pitaevskii-Gross equation

Nonlinear waves, solitary and periodic, are studied exactly in the Pitaevskii-Gross equation for the wave function of the condensate of a superfluid. We also study the relationship between these two waves and Bogoliubov's phonon, and the energies associated with these waves. The creation energy of a solitary wave with amplitudeA is proportional toA ^3/2. Solitary waves show interesting behavior on their collision due to their localized character. The effect of collision on solitary waves can be described by the phase shift. We give a formula of the phase shift on a collision of two solitary waves. We further discuss the decay of an arbitrary initial disturbance into solitary waves.On leave from Department of Physics, Kyushu University, Fukuoka, Japan.     

Analytic Flow Design Method for an Automated Distribution Center with Multiple Shipping Areas

An analytic flow design algorithm for an automated distribution center with multiple shipping areas is presented. The main elements of the analytic flow design are the number of devices and the volumes of product flow between the devices. In the design of an automated distribution center, it is necessary to satisfy the demand throughput while minimizing construction costs. In the conventional design process, system engineers utilize experimental and intuitional approaches. However, conventional approaches are time-consuming and the design outcome is dependent on the skill of the designer. Therefore, a theoretical design algorithm is needed. We propose an analytic flow design algorithm using a dynamic network flow model and considering time-variable flow volumes according to shipment and storage schedules. To verify the feasibility of the proposed method, we perform analytic flow design using real data and confirm that the proposed method can yield a feasible analytic flow design in several minutes.     

Chemical processing and characterization of spinel-type thermistor powder in the Mn-Ni-Fe oxide system

The coprecipitated Mn-Ni-Fe oxalate was prepared from the mixed sulfate solution by optimum pH control. The chemical composition agreed well with that of the starting solution, and the thermal decomposition of the Mn-Ni-Fe oxalate in air below 600 °C led to the direct formation of cubic spinel phase with fine particle size. The sinterability of the calcined powder, the stability of cubic spinel phase and the influence of annealing temperature on electrical properties of the sintered bodies, were investigated.     

Resonance Effect on the Tunneling Reaction: H+H2→H2+H in Solid Hydrogen

The tunneling abstraction reaction: H+H₂H₂+H in -irradiated solid hydrogen has been studied using electron spin resonance (ESR) and electron-nuclear double resonance (ENDOR) spectroscopy and gas-chromatography. The rate constant for the tunneling reaction in solid hydrogen was found to decrease with the increase in the concentration of ortho-H₂ molecules in solid hydrogen. We concluded that the decrease in the rate constant is due to the energy level mismatching between reactant species of H+H₂ trapped and product species of H₂+H trapped in the reverse induced by inhomogeneous intermolecular interactions between ortho-H² molecules in solid hydrogen. This result indicates that resonance effects play an important role in tunneling reactions in solids.     

A photoimmobilizable sulfobetaine-based polymer for a nonbiofouling surface

A novel photoreactive polymer containing sulfobetaine polar groups was prepared by copolymerization of two kinds of methacrylic acids with sulfobetaine and azidoaniline. The polymer was photoimmobilized on polyester and polystyrene surfaces. Its effects on surface modification were investigated from its interactions with water, proteins and cells. Polymer immobilization altered both of the plain surfaces to becoming hydrophilic in a similar range of static contact angles (12.5 ± 1.6° on polyester and 14.7 ± 2.2° on polystyrene). This suggests that the surfaces were covered with sulfobetaine polar groups. Micropattern immobilization was carried out on both polymers using a photomask. The formed pattern was identical to the photomask, showing that the polymer was formed in response to ultraviolet irradiation. Measurements using atomic force microscopy showed that the polymer was formed at a thickness of 550 nm, demonstrating that the polymer was cross-linked with itself and with the substrate molecules. Measurements using time-of-flight secondary ion mass spectrometry detected an abundance of sulfur-containing ions in the patterned polymer, confirming that sulfobetaine had been immobilized. Protein adsorption and mammalian cell adhesiveness were reduced markedly on the immobilized regions. The reduction of cell adhesiveness was concentration-dependent for the immobilized polymer on polyester surfaces. In conclusion, a novel sulfobetaine-containing polymer was immobilized photoreactively on conventional polymer surfaces and significantly reduced interactions with proteins and mammalian cells.     

Solvent free mechanochemical synthesis of MnO2 for the efficient degradation of Rhodamine-B

MnO₂ nanorods were synthesized by mechanochemical processing with subsequent heat treatment and their photocatalytic activity was studied on the decolourization of aqueous solution of Rhodamine B at different pH levels. A solid state redox reaction 2KMnO₄ + MnCl₂ → 3MnO₂ + 2KCl + O₂ was activated during mechanical milling. Excess KCl salt was added in the starting powder mixture to prevent agglomeration of MnO₂ nanoparticles. The milling resulted in the production of amorphous MnO₂ nanoparticles with a high surface area of 204 m² g^?1. Crystalline MnO₂ nanorods of diameters about 15–20 nm were produced by heating the as-milled powder at 350 °C for 1 h in air. Amorphous MnO₂ nanoparticles showed higher degradation rate of Rhodamine B than crystalline MnO₂ nanorods under simulated sunlight. The degradation rate was higher under acidic conditions. This work demonstrates the potential for cost effective, green and scalable synthesis of MnO₂ nano-catalysts for environmental applications.     

Suppression of interface degradation in InGaAsP inP buried heterostructure lasers

In InGaAsP/InP buried heterostructure (BH) lasers, the degradation of BH interface between first- and second-growth step layers can be suppressed by employing the melt back process just before the second-step layer growth. It is confirmed this burying process give more reliable BH lasers than the conventional burying process. From the viewpoint of BH interface degradation, lasers lasing at 1.5 μm, where the melt back process naturally occurs during BH formation, are found to be more reliable than those lasing at 1.3 μm.     

Influencing factors for diamond formation from several starting carbons

The possible influencing factors for diamond formation which prevent non-graphitic carbons from transforming to diamond in the presence of nickel as solvent-catalyst were pursued. The relative amount of nickel to carbon did not affect the behaviour of each starting carbon on diamond formation. The existence of a graphitic structure in the starting carbon was not the major prerequisite for diamond formation. Adsorbed gases on the starting carbon and atmospheric gases in the high pressure cell were found to be the most important influencing factors for diamond formation. Hydrogen and chemical species containing hydrogen atoms were the most harmful.