Characteristic features in the collision of chemical waves depending on the aspect ratio of a rectangular field

The photosensitive Belousov-Zhabotinsky (BZ) reaction was investigated on a double rectangular field composed of two rectangular routes, which was drawn using computer software and then projected using a liquid-crystal projector on a filter paper soaked with BZ solution. When two chemical waves were generated on the rectangular routes as the initial condition, the nature of the collision of the waves could be theoretically classified into four categories depending on the initial phase difference between the two waves and the aspect ratio of the rectangular routes. The experimental results were consistent with the features of the theoretical prediction. These results suggest that the feature of wave propagation characteristically develops depending on the geometry of the excitable fields.     

Highly diastereoselective synthesis of tetrahydrobenzofuran derivatives by palladium-catalyzed reaction of propargylic esters with substituted β-dicarbonyl compounds

Reactions of propargylic esters with 2-substituted cyclohexane-1,3-diones and 2-oxocyclohexanecarboxylic esters in the presence of palladium catalyst are described. Substituted tetrahydrobenzofuran derivatives having a quaternary carbon stereocenter were synthesized in a highly diastereoselective manner.     

Micro-channel fabrication by femtosecond laser to arrange neuronal cells on multi-electrode arrays

The surface of a single-crystal germanium wafer was transformed to crystals of germanium fluorides and oxides upon exposure to a vapor of HF and HNO₃ chemical mixture. Structure analysis indicates that the transformation results in a germanate polycrystalline layer consisting of germanium oxide and ammonium fluogermanate with preferential crystal growth orientation in 〈101〉 direction. Local vibrational mode analysis confirms the presence of N–H and Ge–F vibrational modes in addition to Ge–O stretching modes. Energy dispersive studies reveal the presence of hexagonal α-phase GeO₂ crystal clusters and ammonium fluogermanates around these clusters in addition to a surface oxide layer. Electronic band structure as probed by ellipsometry has been associated with the germanium oxide crystals and disorder-induced band tailing effects at the interface of the germanate layer and the bulk Ge wafer. The acid vapor exposure causes Ge surface to emit yellow photoluminescence at room temperature.     

Preparation of isotactic‐rich poly(dimethyl vinylphosphonate) and poly(vinylphosphonic acid) via the anionic polymerization of dimethyl vinylphosphonate

A vinylphosphonate monomer, dimethyl vinylphosphonate (DMVP), has been polymerized by anionic initiators. Anionic polymerization of DMVP with tert‐butyllithium (t‐BuLi) in combination with a Lewis acid, tributylaluminum (n‐Bu₃Al), in toluene proceeded smoothly to give an isotactic‐rich poly(dimethyl vinylphosphonate) (PDMVP) with relatively narrow molecular weight distribution. Although all the PDMVPs were soluble in water, the isotactic‐rich PDMVP was insoluble in acetone and in chloroform which are good solvents for an atactic PDMVP prepared by radical polymerization. The isotactic‐rich PDMVP showed higher thermal property than that of the atactic PDMVP. Moreover, we successfully prepared poly(vinylphosphonic acid) (PVPA) through the hydrolysis of the isotactic‐rich PDMVP, which formed a highly transparent, self‐standing film. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1677–1682, 2010     

Oxoferryl porphyrin/hydrogen peroxide system whose behavior is equivalent to hydroperoxoferric porphyrin

The reaction between H(2)O(2) and a pyridine-coordinated ferric porphyrin encapsulated by a cyclodextrin dimer yielded a hydroperoxoferric porphyrin intermediate, PFe(III)-OOH, which rapidly decomposed to oxoferryl porphyrin (PFe(IV)═O). Upon reaction with H(2)O(2), PFe(IV)═O reverted to PFe(III)-OOH, which was converted to carbon monoxide-coordinated ferrous porphyrin under a CO atmosphere. PFe(IV)═O in the presence of excess H(2)O(2) behaves as PFe(III)-OOH.     

Evaluation of time-accelerated irradiation method of elastomer by modulus–ultimate elongation profile

“Generalized modulus–ultimate elongation profile” was induced from the relationship between the modulus and the ultimate elongation of an elastomer that was quantitatively added crosslinking and scission. This profile can be used to evaluate the time-accelerated irradiation methods of ethylene-propylene-diene elastomer. The irradiation under low dose rate (0.33 kGy/h) at room temperature was the reference condition. The short-time irradiation condition was 4.2 kGy/h in 0.5 MPa oxygen at room temperature and 5.0 kGy/h in air at 70 °C. The former tended to bring about the higher ratio of scission than the reference condition; the latter tended to bring about the higher ratio of crosslinking.     

The structure of a new cardenolide diglycoside and the biological activities of eleven cardenolide diglycosides from Nerium oleander

A new cardenolide diglycoside (1) was isolated from Nerium oleander together with ten known cardenolide diglycosides 2-11. The structure of compound 1 was established on the basis of their spectroscopic data. The in vitro anti-inflammatory activity of compounds 1-11 was examined on the basis of inhibitory activity against the induction of the intercellular adhesion molecule-1 (ICAM-1). Compounds 2-5 were active at an IC(50) value of less than 0.8 μM. The cytotoxicity of compounds 1-11 was evaluated against three human cell lines normal human fibroblast cells (WI-38), malignant tumor cells induced from WI-38 (VA-13), and human liver tumor cells (HepG2). Compound 3 was active toward VA-13 cells, and compounds 2-5 were active toward HepG2 cells at IC(50) values of less than 1.3 μM. The multidrug resistance (MDR)-reversal activity of compounds 1-11 was evaluated on the basis of the amount of calcein in MDR human ovarian cancer 2780AD cells in the presence of each compound. Compounds 1 and 8 showed moderate effects on calcein accumulation.     

Simultaneous quantitation of sphingoid bases and their phosphates in biological samples by liquid chromatography/electrospray ionization tandem mass spectrometry

We developed a liquid chromatography/electrospray ionization tandem mass spectrometry method for the simultaneous quantitative determination of C18 sphingosine (Sph), C18 dihydrosphingosine (dhSph), C18 phytosphingosine (pSph), C18 sphingosine-1-phosphate (S1P), C18 dihydrosphingosine-1-phosphate (dhS1P), and C18 phytosphingosine-1-phosphate (pS1P). Samples were prepared by simple methanol deproteinization and analyzed in selected reaction monitoring modes. No peak tailing was observed on the chromatograms using a Capcell Pak ACR column (1.5 mm i.d. × 250 mm, 3 μm, Shiseido). The calibration curves of the sphingoids showed good linearity (r > 0.996) over the range of 0.050-5.00 pmol per injection. The accuracy and precision of this method were demonstrated using four representative biological samples (serum, brain, liver, and spleen) from mice that contained known amounts of the sphingoids. Samples of mice tissue such as plasma, brain, eye, testis, liver, kidney, lung, spleen, lymph node, and thymus were examined for their Sph, dhSph, pSph, S1P, dhS1P, and pS1P composition. The results confirmed the usefulness of this method for the physiological and pathological analysis of the composition of important sphingoids.