Column chromatographic pre-concentration of iron(III) in alloys and biological samples with 1-nitroso-2-naphthol-3,6-disulphonate and benzyldimethyltetradecylammonium-perchlorate adsorbent supported on naphthalene using atomic absorption spectrometry

The solid ion-pair material produced from the reaction between benzyldimethyltetradecylammonium chloride (BDTA) and sodium perchlorate on naphthalene provides the basis for a simple, rapid and selective technique for pre-concentrating iron from up to 500 ml of aqueous solution. Iron reacts with disodium 1-nitroso-2-naphthol-3,6-disulphonate (Nitroso-R salt) to form a water-soluble coloured chelate anion. The iron chelate anion forms a water-insoluble, stable iron-Nitroso-R-BDTA complex on naphthalene packed in a column. Trace amounts of iron are quantitatively retained on naphthalene in the pH range 3.5-7.5 and at a flow-rate of 1-2 ml min-1. The solid mass is dissolved out from the column with 5 ml of N,N-dimethylformamide and iron is determined by means of an atomic absorption spectrometer at 248 nm. The calibration graph is linear for concentrations of iron over the range of 0.5-20 micrograms in 5 ml of final solution. The standard deviation and relative standard deviation were calculated. The detection limit of the method was 0.0196 micrograms ml-1 of iron. The sensitivity for 1% absorption was 0.072 microgram ml-1 (0.165 microgram ml-1 by direct atomic absorption spectrometry of aqueous solution). The proposed method was applied to the determination of iron in standard alloys and biological samples.     

Picosecond IR-UV pump-probe spectroscopic study of the dynamics of the vibrational relaxation of jet-cooled phenol. I. Intramolecular vibrational energy redistribution of the OH and CH stretching vibrations of bare phenol

The intramolecular vibrational energy redistribution (IVR) of the OH stretching vibration of jet-cooled phenol-h6 (C6H8OH) and phenol-d8 (C6D8OH) in the electronic ground state has been investigated by picosecond time-resolved IR-UV pump-probe spectroscopy. The OH stretching vibration of phenol was excited with a picosecond IR laser pulse, and the subsequent temporal evolutions of the initially excited level and the redistributed ones due to the IVR were observed by multiphoton ionization detection with a picosecond UV pulse. The IVR lifetime for the OH stretch vibration of phenol-h6 was determined to be 14 ps, while that of the OH stretch for phenol-d8 was found to be 80 ps. This remarkable change of the IVR rate constant upon the dueteration of the CH groups strongly suggests that the "doorway states" for the IVR from the OH level would be the vibrational states involving the CH stretching modes. We also investigated the IVR rate of the CH stretching vibration for phenol-h6. It was found that the IVR lifetime of the CH stretch is less than 5 ps. The fast IVR is described by the strong anharmonic resonance of the CH stretch with many other combinations or overtone bands.     

Two-color multiphoton ionization of diazabicyclooctane in a supersonic free jet

Two-color multiphoton ionization (MPI) spectroscopy has been applied for diazabicyclooctane (DABCO) in a supersonic free jet. The MPI spectra due to transitions from the various vibronic levels of the S₁ (3s Rydberg) state which were excited by the first laser revealed the high Rydberg states above the adiabatic ionization potential. The ionization process and the vibrational potential of the ion are discussed.     

Morphology of protonated methanol clusters: an infrared spectroscopic study of hydrogen bond networks of H+(CH3OH)n (n = 4-15)

Infrared spectroscopy of large-sized protonated methanol clusters, H(+)(MeOH)(n) (n = 4-15), was carried out in the OH stretch region to characterize the development of the hydrogen bond network with the cluster size, n. The band intensity of the free OH stretching mode decreased with n, and the band finally disappeared at n = 7. On the other hand, the broad absorption band due to hydrogen-bonded OH stretches exhibited a remarkable shift with the cluster size, and it finally converged on 3300 cm(-1) for n >/= approximately 10. The size dependence of the infrared spectra was morphologically interpreted in terms of the formation of the bicyclic hydrogen-bonded structure of the clusters.     

Polymerized Complex Route to the Synthesis of Pure SrTiO3 at Reduced Temperatures: Implication for Formation of Sr-Ti Heterometallic Citric Acid Complex

Powders of SrTiO3 were prepared by the Pechini-type polymerized complex technique, wherein a mixed solution of citric acid (CA), ethylene glycol (EG), Sr and Ti ions with a molar ratio of CA/EG/Sr/Ti = 10/40/1/1 was polymerized at 130°C to produce a yellowish transparent polyester-type resin without undergoing precipitation, which after decomposition on heating at 350°C was used as a powder precursor for SrTiO3. The formation of pure perovskite SrTiO3 practically free from carbonates occurred when the powder precursor was heat treated at temperatures higher than 500°C in static air. No X-ray diffraction and Raman spectroscopic evidence for phase separation of crystalline SrCO3 and TiO2 as distinct intermediates has been obtained during the thermal decomposition of the powder precursor, suggesting the molecular-scale mixing of cations in the Sr-Ti powder precursor. 13C-NMR spectroscopic measurements have indicated that unusual alkoxylation of CA occurred exclusively when both strontium and titanium ions in equal amounts coexist in CA/EG solutions, the phenomenon of which was discussed in connection with possible formation of a Sr-Ti heterometallic CA complex. The number of CA participating in formation of (Sr, Ti)-CAn was estimated to be n 3 from the variation of 13C-NMR spectra with relative concentrations of metal ions and CA. This heterometallic complex was thermally stable in CA/EG solutions upon heating at 130°C, implying that the molecular-level homogeneity achieved in the Sr/Ti precursor solution was preserved throughout the polymerization process.     

Total synthesis of salinosporamide A

The total synthesis of salinosporamide A has been achieved through enzymatic desymmetrization, diastereoselective aldol reaction, intramolecular aldol reaction, and intermolecular Reformatsky-type reaction followed by 1,4-reduction as key reactions.     

Incubation type Si-based planar ion channel biosensor

A new planar-type ion channel biosensor with the function of cell culture has been fabricated using silicon on an insulator substrate as the sensor chip material. Coating of the sensor chip with fibronectin was essentially important for cell incubation on the chip. Although the seal resistance was quite low (∼7 MΩ) compared with the pipette patch-clamp gigaohm seal, the whole-cell channel current of the transient receptor potential vanilloid type 1 (TRPV1) channel expressing HEK293 cells was successfully observed, with a good signal-to-noise ratio, using capsaicin as a ligand molecule. Figure A new planer type ion channel biosensor with function of cell culture is fabricated using the silicon on insulator substrate as the sensor chip material. The coating of the sensor chip by the fibronectin was essentially important for the cell incubation on the chip. Whole cell channel current of TRPV1 channel was successfully observed using capsaicin as a ligand molecule with good signal to noise.     

Optical magnetoelectric effect of patterned oxide superlattices with ferromagnetic interfaces

Nonreciprocal directional dichroism, termed the optical magnetoelectric (OME) effect, has been observed in patterned superlattice (SL) composed of perovskite oxides, LaMnO3, SrMnO3, and LaAlO3. Such a tricolor SL with ferromagnetic interfaces is expected to artificially break both space-inversion and time-reversal symmetries and hence to show the OME effect. The Bragg diffraction from the grating structure with a period of 4 microm fabricated on the SL was employed to sensitively detect the OME effect, yielding the relative change of the diffracted light intensity (~0.2%-0.5%) upon a reversal of either the in-plane magnetization or the propagation vector of the diffracted light.     

Formation of "snowmanlike" polystyrene/poly(methyl methacrylate)/toluene droplets dispersed in an aqueous solution of a nonionic surfactant at thermodynamic equilibrium

"Snowmanlike" polystyrene (PS)/poly(methyl methacrylate) (PMMA) composite particles were prepared by evaporation of toluene from PS/PMMA/toluene droplets dispersed in an aqueous solution of polyoxyethylene nonylphenyl ether surfactant (Emulgen 911). Partitioning experiments revealed that the Emulgen 911 concentration was higher in the droplets than in the aqueous solution during toluene evaporation. As a consequence, the interfacial tensions between the polymer phases (PS and PMMA) and the aqueous phase (gammaP-T/W) were extraordinarily low (approximately 10(-1) mN/m). The interfacial tension between the PS and PMMA phases containing toluene (gammaPS-T/PMMA-T) measured by the spinning drop method was not affected by the presence of Emulgen 911. Based on minimization of the total interfacial free energy at a polymer weight fraction in the toluene droplet of 0.17, the formation of spherical droplets is expected, in agreement with experiment. The subsequent morphology change of the PS/PMMA/toluene droplets from spherical to snowmanlike during toluene evaporation under thermodynamic equilibrium is attributed to (i) the low values of gammaP-T/W, which explains the increase in the interfacial area between the droplets and the aqueous phase, and (ii) the increase in gammaPS-T/PMMA-T with increasing polymer weight fraction.