Aqueous solutions of sodium methylsulfate by Raman scattering,NMR, ultrasound,and density measurements

Dynamic properties of sodium methylsulfate were investigated by means of NMR and Raman spectroscopies. The concentration dependence of the spin-lattice relaxation times of²³Na in aqueous solutions of sodium methylsulfate show no detectable specific interactions between sodium and methylsulfate ions. Raman band profiles of the S-O stretching mode of methylsulfate ion in aqueous solution show asymmetry above about 3.0 mol-dm^–3. Furthermore, the proton spin-lattice relaxation rates of the methylsulfate ion in D₂O increase linearly up to about 3.0 mol-dm^–3, but above this concentration they deviate from linearity.These experimental results indicate that dynamic properties of methylsulfate ion are affected by ion-water interactions. Raman band asymmetry is attributed to the non-uniformity of the distribution of water molecules around the methylsulfate ion. This interpretation is supported by the theory developed by Knapp and Fischer. The distortion of the distribution of water molecules around ions is also discussed on the basis of the overlap of the hydration layer around methylsulfate ion which is estimated by the measurement of sound velocity and density.     

Characterization of zinc-modified lithium tantalate thin films fabricated by chemical solution deposition method

Zinc-substituted lithium tantalate thin films were fabricated for improving the electrical resistivity by compensating the valence of lattice defects in LiTaO₃ crystal. The films with the chemical composition of (Li_1.00-x Zn _x )TaO₃ were fabricated on (111)Pt/TiO₂/SiO₂/(100)Si substrate by a chemical solution deposition technique using metal-organic precursors. Dense films consisting of a ilumenite-type crystalline phase were deposited by spin coating on the substrates, followed by heat-treatment at 650°C for 5 min in air. The leakage current density of the LiTaO₃ film was reduced from approximately 10⁻⁴ to 10⁻⁶ A/cm² by substituting Zn²⁺ ions for Li⁺ ions in the LiTaO₃ films. Polarization–electric field hysteresis loop was improved significantly by partial substitution of Zn²⁺ for Li⁺ ions, which is based on the enhancement of electrical resistivity.     

Specific activities of radioactive elements from fission product mixtures

Specific activities of radioactive elements at the time of chemical separation from fission product mixtures produced by thermal neutron fission of²³⁵U were computed byBateman's and other equations on an electronic computer. Computations were made for two fission times: fission was assumed to be complete in a few minutes in one case, and over a period of a year in the other case. It was also assumed that each element was separated instantly after allowing the fission products to decay for 1∼10 000 000 hrs (1 140 years). The computations were applied to 12 important elements: Ru, Zr, Nb, Cs, Sr, Pm, Tc, Ba, La, Ce, Kr and Y. Results are given as a diagram for each element. The diagrams are intended to be helpful in the chemical processing of a large quantity of fission products, and industrial or tracer application of these elements.     

Gene transfection into adherent cells using electroporation on a dendrimer-modified gold electrode

Gene transfection into adherent cells from plasmid DNA (pDNA)-arrayed substrates known as gene transfection arrays appears to be a promising tool for the high-throughput analysis of gene functions and protein-protein interaction networks. We tested the ability of electric pulse-stimulated gene transfection from a substrate to overcome low expression efficiency and cross contamination between spots on arrays. We prepared the electrodes used for electric pulse-stimulated gene transfection by sequentially loading a gold thin layer, a self-assembled monolayer of a carboxylic acid-terminated alkanethiol (COOH-SAM), and poly(amidoamine) (PAMAM) dendrimers, either through electrostatic interactions or by covalent linkage to COOH-SAM and then to pDNA. When dendrimers were loaded onto the electrode using electrostatic interactions, the gene-expression efficiency of adherent cells increased as the generation numbers of the dendrimers that we used increased. Gene expression was rarely observed in adherent cells when dendrimers were covalently immobilized onto the electrode. Additionally, we successfully demonstrated site-specific gene transfer using a dendrimer-array electrode with no cross contamination between spots on the electrode.     

Neutral-to-ionic transition in tetrathiafulvalene-p-chloranil as investigated by optical reflection spectra

Polarized reflection spectra and their temperature-dependence as well are investigated on tetrathiafulvalene-p-chloranil (TTFCA) single crystals over the temperature range from 2 K to room temperature. Abrupt changes are observed at T_c = 84.4 ± 0.5 K in the charge transfer and intramolecular excitation bands. These experimental results strongly indicate that the dominant part of the neutral-to-ionic transition in this crystal takes place at a sharply defined critical temperature, in contrary to the recent observation by Torrance et al. [Phys. Rev. Lett.47, 1747 (1981)] that the transition occurs in a temperature range of about 30 K in width. A simple model is presented to account for the observed shift of the TTF⁺ intramolecular transition bands at T_c.     

Double Doppler ranging system using FM ultrasound

A new system which detects change in distance between a sound source and a receiver, using FM ultrasound has been developed, the principle of which is based on the Doppler phase shift. The use of FM ultrasound allows simultaneous detection both by carrier signal and by demodulated signal, and by using these methods together, stable measurements with good resolution are possible. Experiments in air and an anechoic water tank confirmed the accuracy of plus or minus half a wavelength for change of distance.     

Experimental determination of the charge-transfer exciton band width in anthracene-PMDA crystal

The charge-transfer (CT) exciton is investigated on the reflection and luminescence spectra of isotopically mixed anthracene-PMDA crystals. The observed features are analyzed by the coherent potential approximation. It is concluded that the CT exciton in this crystal has the band width of about 100 cm^?1.