Combinatorial and approximative analyses in a spatially random division process

For a spatial characteristic, there exist commonly fat-tail frequency distributions of fragment-size and -mass of glass, areas enclosed by city roads, and pore size/volume in random packings. In order to give a new analytical approach for the distributions, we consider a simple model which constructs a fractal-like hierarchical network based on random divisions of rectangles. The stochastic process makes a Markov chain and corresponds to directional random walks with splitting into four particles. We derive a combinatorial analytical form and its continuous approximation for the distribution of rectangle areas, and numerically show a good fitting with the actual distribution in the averaging behavior of the divisions.     

Sonochemical preparation of composite nanoparticles of Au/gamma-Fe2O3 and magnetic separation of glutathione

We prepared Au/gamma-Fe2O3 composite nanoparticles by sonochemically reducing Au(III) ions employing no stabilizer in the aqueous solution to form stable Au nanoparticles and allowing them to attach onto the surface of gamma-Fe2O3 particles with an average size of 21 nm. Size of the formed Au nanoparticle depended on the initial concentration of Au(III) ions. The number of the Au nanoparticles, supported on each gamma-Fe2O3 particle was controlled by changing the relative amounts of Au(III) ions and gamma-Fe2O3 particles. The composite nanoparticles exhibited a high affinity with glutathione, a tripeptide with mercapto group so that separation and manipulation of glutathione in aqueous solutions could be performed by application of external magnetic field. Because the surfaces of the Au nanoparticles were not shielded by any stabilizers, or naked, sonochemically prepared Au/gamma-Fe2O3 composite nanoparticles seemed to show stronger affinity to the glutathione than those by the radiochemical method.     

Observation of the transient rotator phase of n-hexadecane in emulsified droplets with time-resolved two-dimensional small- and wide-angle X-ray scattering

Crystallization of n-hexadecane in emulsion droplets was studied using time-resolved two-dimensional small- and wide-angle x-ray scattering with differential scanning calorimetry (2D-SAXS-WAXS-in situ DSC) which provides information about both nano- and subnanoscale structural change. n-hexadecane in droplets reproducibly crystallized into the stable triclinic phase via a transient-rotator phase. This is in contrast with previous results that the rotator phase of n-hexadecane was observed only occasionally for bulk samples. Thus we confirmed the existence of rotator phase in n-hexadecane, which is important for the study of crystallization of soft materials. We suggest that the rotator phase at the interface of oil and water plays a precursor role for bulk crystallization. This study demonstrates that 2D-SAXS-WAXS-in situ DSC is a powerful tool for the study of a transient phase.     

Effect of suspended particles on spreading of volatile droplet on solid substrate

Abstract  

We have been interested in behaviors of suspended particles in a volatile droplet placed on a smooth substrate. It is known that the particles gather and deposit in the vicinity of the macroscopic contact line of the droplet, which is generally called ‘coffee stain problem’. A convective flow induced by non-uniform evaporation through the interface brings suspended particles toward the pinned contact line in the drying droplet, which forms a ring stain. We have focused on the dynamics of the droplet with/without suspended particles spreading on the solid substrate and on the behaviors of particles in the evaporating droplet. Spreading process of the droplet is significantly affected by the suspended particles. We indicate flow patterns in the droplet, in which the flow exhibits a modal structure with a mode number in the azimuthal direction, and indicate particles depositions after the dryout of the droplet. Three-dimensional particle tracking velocimetry is applied to reconstruct such unique flow patterns in the spreading process of the droplet. Resultant patterns of the particles depositing on the substrate are introduced.     

Influence of intramolecular vibrations in charge redistribution at the pentacene-graphite interface

We have investigated the relation between the intramolecular vibrational modes of pentacene and the charge redistribution at the pentacene-graphite interface by using high-resolution electron-energy-loss-spectroscopy. The three main vibrational peaks shift to lower energies as the pentacene film thickness decreases. In order to discuss this energy shift, we have calculated the vibrational energies of a free pentacene molecule by changing its charge state. We have also calculated the vibrational energies of a pentacene molecule adsorbed on a graphite sheet by changing the pentacene-graphite distance. Taking the experimental and calculation results into account, we conclude that the observed energy shifts result from an intramolecular charge redistribution. The present results indicate that the effect of an intramolecular charge redistribution is essential to discuss the origin of an energy shift observed in a vibrational study of an organic molecule/substrate interface.     

Unitary representations of the quantum group SU q (1,1): Structure of the dual space ofU q (sl(2))

Real forms of the quantum universal enveloping algebraU _q (sl(2)) and a topological quantum group associated with this algebra are discussed.     

Evaluation of immobilized-lysozyme by means of TOF-SIMS

Evaluation of immobilized-proteins on bio-devices is important for the development of sophisticated devices. Lysozyme molecules immobilized on substrates were evaluated by means of time-of-flight secondary ion mass spectrometry (TOF-SIMS). Two types of the lysozyme-immobilized samples were prepared by controlling the binding parts, i.e., the amino groups or carboxyl groups, of the protein. The TOF-SIMS spectra of each sample were analyzed with mutual information to select fragment ions specific to each sample. According to the results, differences between the samples being immobilized in the different ways are suggested, and the surface structure of the lysozyme molecule immobilized at amino groups is determined based on three-dimensional structure of lysozyme in the Protein Data Bank.