Uncertainty index based interval assignment by Interval AHP

In a multi-attribute decision making problem, indigenous values are assigned to attributes based on a decision maker’s subjective judgments. The given judgments are often uncertain, because of the uncertainty of situations and intuitiveness of human judgments. In order to reflect the uncertainty in the assigned values, they are denoted as intervals whose widths represent the possibilities of attributes. Since it is difficult for a decision maker to assign values directly to attributes in case of more than two attributes, he/she gives a pairwise comparison matrix by comparing two attributes at one occasion. The given matrix contains two kinds of uncertainty, one is inconsistency among comparisons and the other is incompleteness of comparisons. This paper proposes the models to obtain intervals of attributes from the given uncertain pairwise comparison matrix. At first, the uncertainty indexes of a set of intervals are defined from the viewpoints of entropy in probability, sum or maximum of widths, or ignorance. Then, considering that too uncertain information is not useful, the intervals of attributes are obtained by minimizing their uncertainty indexes.     

Control of self-aggregation of fullerenes by connection with calix[4]arene: solvent- and guest-effects to particle size

A new molecular design of fullerene derivatives exhibiting trigger-responsive self-aggregation in organic solvents has been established. Calix[4]arene was covalently connected with fullerene in order to apply host-guest interaction to the aggregation control. The self-assembly behaviour was studied in organic solvents by UV-vis absorption spectroscopy, dynamic light scattering and transmission electron microscopy. Results show that the bisfullerene formed self-aggregations with a low polydispersity index due to the fullerenes' tendency to aggregate in polar organic solvents. Furthermore, the aggregate sizes can be changed readily by solvent composition and the addition of guest cations. Especially, disaggregation of the bisfullerene was induced by addition of LiClO4 or NaClO4.     

Single-walled carbon nanotubes template the one-dimensional ordering of a polythiophene derivative

We have used a mechanochemical high-speed vibration milling (HSVM) technique to solubilize single-walled carbon nanotubes (SWNTs) in organic solvents through the formation of complexes between the SWNTs and a polythiophene (PT) derivative. This HSVM approach is superior to the conventional sonication method used to solubilize SWNTs in organic solvents. Moreover, we found that in these supramolecular complexes the PT chains were ordered one-dimensionally on the SWNT surfaces in organic solvents. [structure: see text].     

Molecular structure of agarose chains in thermoreversible hydrogels revealed by means of a fluorescent probe technique

Thermoreversible hydrogels of agarose with both high and low molecular weights were studied by means of a fluorescence probe method using 1‐anilino‐8‐naphthalene sulfonic acid (ANS). The fluorescence spectra of ANS in agarose/water changed markedly with agarose concentration. Analysis of the spectra shows that this change is not due to a shift of the whole spectrum, but that there are two fluorescent components of ANS in addition to the fluorescence peak at 542 nm due to free ANS molecules in water. The fluorescence component at 461 nm is assumed to be from ANS intercalated within either a single 3₁ helix‐form agarose chain or nonpolar region produced by chemical defect, and the fluorescence component between 507 and 522 nm is assumed to be from ANS in aggregated regions of agarose chains having a loose helical structure. There is no doubt that a certain number of water molecules are included in the aggregated region. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 680–688, 2005     

Development characteristics of fluctuating velocity field of drag-reducing surfactant solution flow in a duct

Development behavior of the fluctuating velocity of surfactant solution in a duct has been studied experimentally. The concentration of surfactants was kept constant at 1,000 ppm, mean velocity at 0.78 m/s and fluid temperature at 15 °C. Using laser Doppler velocimetry, the fluctuating streamwise velocity distributions at six cross sections, which ranged from 14 to 112 times of hydraulic diameter of the duct, were measured. From the results, the fluctuating structures of surfactant solution flow are observed to have structures different from that of turbulent water flow in the developing field. The wavelet analysis reveals that the high-level fluctuation of surfactant solution flow is characterized by periodicity rather than irregularity around the position where the fluctuation intensity takes a peak value and that the period and the scale of periodic flow structures are related to the relaxation times of the fluid. This indicates that the high-level fluctuation is deeply related to the elastic instability and has a different generation mechanism from that of turbulence observed in a Newtonian turbulent flow.     

Preparation of hemispherical particles by cleavage of micrometer-sized,spherical poly(methyl methacrylate)/polystyrene composite particle with Janus structure: effect of molecular weight

Micrometer-sized, hemispherical polymer particles were prepared as a result of cleavage of spherical Janus poly(methyl methacrylate) (PMMA)/polystyrene (PS) composite particle by treating particles with acetone/water solutions. The original PMMA/PS composite particles were prepared by the slow evaporation of toluene from homogeneous PMMA/PS/toluene droplets dispersed in aqueous solution of sodium dodecyl sulfate in advance. Appropriate molecular weights of PMMA and PS were necessary for occurrence of the cleavage of the Janus composite particle, resulting in PMMA and PS hemispherical particles. The cleavage depended on the composition of the acetone/water solution, which was explained by selective solvent absorption into the polymer phases. The results strongly support the cleavage mechanism of Janus composite polymer particles that had been proposed earlier.     

Preparation of hemispherical polymer particles via phase separation induced by microsuspension polymerization

Micrometer-sized, hemispherical polystyrene (PS) particles were successfully prepared by microsuspension polymerization of homogeneous styrene/hexadecane (HD) droplets dispersed in polyoxyethylene nonylphenyl ether (Emulgen 931) aqueous solution, followed by rapid removal of HD from formed PS/HD particles with a “Janus” structure. It was important for the formation of the morphology of Janus particles in thermodynamically stable state to carry out the polymerization slowly. The formation of by-product small PS particles by emulsion polymerization was suppressed by the additions of CuCl₂ as a water-soluble inhibitor and NaCl to decrease the solubility of styrene in the aqueous phase.     

Interaction of ultraviolet absorbers

Ultraviolet absorbers (UVA) are used in various fields, and their interactions with other additives have been studied. However, the interaction between UVA has not been studied in detail. In this study, the interaction of two UVA having maximum absorption in the range of UV-A (320-400 nm) or UV-B (290-320 nm) was studied. It was found that the photo-oxidation occurs by the fluorescence, which is emitted by a photo-excited UVA-B, if it has enough high energy, that is, its wavelength is within UV-A range. When a UVA-A coexists with such a UVA-B, however, the mixture of both UVA may show a synergism, because the UVA-A absorbs the fluorescence from UVA-B to make it harmless. Particularly, the mixture of hydrogen transfer-type UVA and charge separation-type UVA shows remarkable synergism. The synergistic mechanism is discussed.     

Total synthesis of a novel tetracyclic alkaloid, cassiarin F from the flowers of Cassia siamea

A novel alkaloid, cassiarin F (1), which showed potent antiplasmodial activity against Plasmodium falciparum in vitro, was isolated from the flowers of Cassia siamea, and its structure was elucidated on the basis of 2D NMR analyses. A total synthesis of 1 was also achieved by employing the Suzuki coupling constructing biaryl unit, nucleophilic aromatic substitution, and Houben-Hoesch type ring construction as key steps.     

Synthesis and heteronuclear inclusion properties of a novel thiacalix[4]arene-based hard-soft receptor with 1,3-alternate conformation

A novel thiacalix[4]arene ditopic receptor with 1,3-alternate conformation and possessing two complexation sites for hard and soft cations, 5,11,17,23-tetra-tert-butyl-25,27-bis[(N,N-diethylaminocarbonyl)methoxy]-26,28-bis[(pyridylmethyl)oxy]-2,8,14,20-tetrathiacalix[4]arene is prepared. Regioselective synthesis of distal-bis[(N,N-diethylaminocarbonyl)methoxy]thiacalix[4]arene is accomplished by a protection-deprotection method using benzyl groups as a protecting group. The deprotection of benzyl group was succeeded in the presence of solid superacid (Nafion-H) under refluxing benzene. Its complexation behavior is examined by ¹H-NMR titration experiments. The formation of 1:2 homo- and heteronuclear complexes demonstrates that the preorganization, subtle conformational changes and affinity have a pronounced effect on the complexation of the receptor.