Algebraic structure of association schemes of prime order

Finite groups of prime order must be cyclic. It is natural to ask what about association schemes of prime order. In this paper, we will give an answer to this question. An association scheme of prime order is commutative, and its valencies of nontrivial relations and multiplicities of nontrivial irreducible characters are constant. Moreover, if we suppose that the minimal splitting field is an abelian extension of the field of rational numbers, then the character table is the same as that of a Schurian scheme.     

Polybenzimidazoles containing anthracene photodimer

Polybenzimidazoles that contained anthracene photodimer were prepared. The molecular weights of the polymers prepared by the photopolymerization of bis-anthrylbenzimidazoles were limited by the precipitation of the resulting polymers from the reaction organic solvents. Higher molecular weight polymers were obtained by the photopolymerization of bis-anthryl-Schiff's bases, followed by the oxidation of the resulting polymers. These polymers were soluble in acidic solvents such as formic and sulfuric acids but were insoluble in organic solvents.     

SUPER TOUGH GELS WITH A DOUBLE NETWORK STRUCTURE

 Living tissues work with fantastic functions in soft and wet gel-like state. Thus, hydrogels have attracted much attention as excellent soft & wet materials, suitable for making artificial organs for medical treatments.However, conventional hydrogels are mechanically too weak for practical uses. We have created double network (DN) hydrogels with extremely high mechanical strength in order to overcome this problem. DN gels are interpenetrating network (IPN) hydrogels consisting of rigid polyelectrolyte and soft neutral polymer. Their excellent mechanical properties cannot be explained by the standard fracture theories. In this paper, we discuss about the toughening mechanism of DN gels in accordance with their characteristic behavior, such as large hysteresis and necking phenomenon. We also describe the results on tissue engineering application of DN gels.     

n-sigma charge-transfer interaction and molecular and electronic structural properties in the hydrogen-bonding systems consisting of p-quinone dianions and methyl alcohol

Molecular and electronic structural properties of the hydrogen-bonded complexes of p-quinone dianions (PQ(2)(-)) were investigated by electrochemistry and spectroelectrochemistry of PQ in MeCN combined with ab initio MO calculations. Hydrogen bonding between PQ(2)(-) and MeOH was measured as the continuous positive shift of the apparent second half-wave reduction potentials with increasing concentrations of MeOH. Detailed analyses of the behavior reveal that PQ(2)(-) forms the 1:2 hydrogen-bonded complexes at low concentrations of MeOH and the 1:4 complexes at high concentrations, yielding the formation constants. Temperature dependence of the formation constants allows us to yield the formation energy as 76.6 and 118.9 kJ mol(-)(1) for the 1:2 and 1:4 complex formation of the 1,4-benzoquinone dianion (BQ(2)(-)) with MeOH, respectively. These results show that the pi-dianions involving the quinone carbonyl groups exhibit very strong hydrogen-accepting ability. The longest wavelength band of the spectra of BQ(2)(-) and the chloranil dianion (CL(2)(-)) is assigned to the (1)B(3u) <-- (1)A(g) band mainly contributed from an intramolecular charge-transfer (CT) configuration. Hydrogen bonding allows the band of BQ(2)(-) and CL(2)(-) to be blue-shifted, depending on the strength of the hydrogen bonds. CNDO/S-CI calculations reveal that the blue shift is ascribed to stabilization of the ground state by the hydrogen bonding involving strong n-sigma-type CT interaction. The HF/6-31G(d) calculation results show that the structure of PQ(2)(-) is characterized by a lengthening of the C=O bonds and a benzenoid ring. The geometrical properties of the hydrogen-bonded complexes of PQ(2)(-) are a slight lengthening of the C=O bonds and a short distance of the hydrogen bonds. It is demonstrated that this situation is due to the strong n-sigma CT interaction in the hydrogen bonds. The results suggest that the differing functions and properties of biological quinones are conferred by the n-sigma CT interaction through hydrogen bonding of the dianions with their protein environment.     

Polymerization and copolymerization of methacrylic esters derived from glycidyl methacrylate

Copolymerization of methacrylic esters derived from glycidyl methacrylate and nucleophiles with styrene was carried out. The monomer reactivity ratios of these methacrylic esters were varied with the alkoxy groups of the esters and the solvent used.     

Prospective study to assess the clinical efficacy of bone scintigraphy--some analyses of clinical data

The value of preoperative bone scans in patients with primary breast and prostate cancer was evaluated prospectively. Of 414 patients with breast cancer, clinical stage I is 14, II is 219, IIIA is 59, IIIB is 39 and IV is 14. Of 88 patients with prostate cancer, clinical stage I is 14, II is 15, III is 18 and IV is 41. 11 percent of patients with breast cancer and 54 percent of patients with prostate cancer had bone metastases. Clavicle, ribs, thoracic spine, lumbar spine and pelvis metastasized most frequently. The incidences of bone metastases were 18.4% with Scirrhous carcinoma, 15.4% with Medullary tubular carcinoma and 3.8% with Papillotubular carcinoma. The methodology and results of ROC analysis were described in our other papers. Some results of data analysis were described in this paper.     

Tosylation of endocrine-disruptive alkylphenolic compounds in a solid-phase reaction system consisting of C18-modified silica gel and aqueous buffer solution

The tosylation reaction of endocrine-disruptive alkylphenolic compounds in a solid-phase aqueous system was investigated with the aim of developing an environment-friendly and efficient derivatization method for HPLC analyses of environmental samples. The phenols were rapidly and efficiently converted to the tosyl derivatives on a commercially available ODS solid-phase cartridge by passing an aqueous buffer solution through it. The solid-phase aqueous tosylation system has been incorporated into a preconcentration step performed by solid-phase extraction from environmental water.