Fabrication of a miniature-size pyramidal-shape diamond fieldemitter array

A miniature-size pyramidal-shape diamond field emitter array has been fabricated using the mold technique. The tip radius of each pyramid was found to be less than 2000 Å from SEM observation and the fabricated array was identified as diamond from the results of AES and Raman spectroscopy. The array was placed in a high vacuum pumping system with the basic pressure of 10^-7 Torr, and the emission property was measured using a Au ball anode with 100 μm in diameter. The distance between the anode and the array was set up to 100 μm throughout the measurements. As a result, the emission current of 1×10^-6 A was observed at the applied voltage of 2400 V     

Neutral liposome-mediated delivery process of fluorescein-modified oligonucleotides in cultured human keratinocytes

We propose a model of the intracellular delivery process in which fluorescein-labeled natural oligonucleotides (F-DNA) are transferred into the nuclei of cultured human keratinocytes. By encapsulation in neutral multilamellar lecithin liposomes, the F-DNA appeared to be protected against intracellular interactions with cellular materials and nuclease attacks in the cytoplasm during the process. The intracellular behavior of F-DNA and fluorescent phospholipid-labeled liposomes was observed by means of fluorescence analysis. Results showed that: F-DNA encapsulated in neutral multilamellar liposomes reached the cellular nuclei more efficiently than either free F-DNA, or F-DNA in unilamellar liposomes; the liposomal membranes appeared to be left in the cytoplasm. The reaction of F-DNA with complementary DNA was suggested by a rapid quenching of the fluorescence in the nucleus. In addition, the fluorescence decrease was evidently suppressed in the cytoplasm, indicating a protective effect of the neutral multilamellar liposomes against the interaction of F-DNA with cytoplasmic materials. The application of these findings to ‘photo’-antisense studies has been discussed, where suppression of a gene expression is attempted by using oligonucleotide-attached fluorescein with the aid of a photo-induced covalent binding property.     

Properties and the inclusion behavior of 6-O-alpha-D-galactosyl- and 6-O-alpha-D-mannosyl-cyclodextrins

The novel heterogeneous branched cyclodextrins (CDs), 6-O-alpha-D- galactosyl-alpha, -beta, and -gamma CDs (Gal-alpha, -beta, and -gamma CDs) and 6-O-alpha-D-mannosyl-alpha, -beta, and -gamma CDs (Man-alpha, -beta, and -gamma CDs) dissolved sufficiently in water and in 10-50% (v/v) methanol aqueous solutions, as did the homogeneous branched CDs, 6-O-alpha-D-glucosyl-alpha, -beta, and -gamma CDs (Glc-alpha, -beta, and -gamma CDs). The solubilities of heterogeneous branched CDs were higher than those of each parent non-branched CDs. The hemolytic activities of heterogeneous and homogeneous branched CDs were lower than those of each parent non-branched CDs and the hemolytic activity became weaker in the order of non-branched CD > Man-CD > Glc-CD > Gal-CD in each series of alpha, beta, and gamma CD. AL type solubility-phase diagrams were displayed in the formation of inclusion complexes of the guest compounds of small size (methyl benzoate, estriol, and dexamethasone) with Gal-, Man-, and Glc-CDs, and marked differences among the three kinds of branched CDs could not be detected. However, solubility-phase diagrams between these branched CDs and the insoluble guest compounds of large cyclic structure (cyclosporin A, tacrolimus, and amphotericin B) showed AP type, and the improvement of water solubilities of these guest compounds with three kinds of branched CDs was enhanced in the order of Man-CDs > Glc-CDs > Gal-CDs.     

Transfer of diclofenac sodium across excised guinea pig skin on high-frequency pulse iontophoresis. I. Equivalent circuit model

High frequency pulse iontophoresis of diclofenac sodium across excised guinea-pig skin was carried out in vitro. An equivalent circuit model was constructed to simulate the time courses of voltage drop across the donor solution and the skin. Parameter values obtained by the least-squares adaptation of the model to observed data were consistent with expectation and validated the proposed model.     

Analysis of toxic elements by MPGA

In order to improve the sensitivity for the quantification of trace elements, we propose the combination of prompt gamma-ray analysis (PGA) and a multiple gamma-ray detection method. A new Ge detector system for multiple prompt gamma-ray analysis (MPGA) was constructed at the neutron guide-hall of the JRR-3M reactor of the Japan Atomic Energy Agency (JAEA). The first demonstration of this system was given with a plastic sample containing traces of cadmium. The quantification limit of cadmium in a plastic sample was found to be about 0.1 ppm.     

Phase equilibrium in the system Ln-Mn-O: V. Ln=Yb and Dy at 1100°C

Phase equilibrium was established in the Yb-Mn-O and Dy-Mn-O systems at 1100°C by varying the oxygen partial pressure from −log (P_O2/atm)=0-13.00, allowing construction of phase diagrams at 1100°C for the systems Ln₂O₃-MnO-MnO₂. Under experimental conditions, Yb₂O₃, MnO, Mn₃O₄, and YbMnO₃ phases are found to be present in the Yb-Mn-O system, whereas Dy₂O₃, MnO, Mn₃O₄ DyMnO₃, and DyMn₂O₅ phases are present in the Dy-Mn-O system. Ln₂MnO₄, Mn₂O₃, and MnO₂ are not stable in either system. Small nonstoichiometric ranges are found in the LnMnO₃ phase, with the nonstoichiometry represented by the equations, N_O/N_YbMnO3=1.00×10⁻⁴(log P_O2)³+1.30×10⁻³(log P_O2)²+7.20×10⁻³(log P_O2)+5.00×10⁻⁵ and N_O/N_DyMnO3=1.00×10⁻⁴(log P_O2)³+1.80×10⁻³(log P_O2)²+9.30×10⁻³(log P_O2)+1.69×10⁻². Activities of the components in the solid solutions are calculated using these equations. LnMnO₃ may range Ln₂O₃-rich to Ln₂O₃-poor, while MnO is slightly nonstoichiometric to the oxygen-rich side. DyMn₂O₅ also seems to be nonstoichiometric. Lattice constants of LnMnO₃ under different oxygen partial pressures were determined, as well as lattice constants of DyMn₂O₅ quenched in air. The standard Gibbs energy changes of reactions appearing in the phase diagrams were calculated.     

Novel benzyl sulfonium salt having an aromatic group on sulfur atom as a latent thermal initiator

Three benzyl p-hydroxyphenyl methylsulfonium salts with different counter anions were synthesized as novel latent thermal initiators. Syntheses of the sulfonium salts ( 2 ) were performed by the reaction of p-hydroxyphenyl methyl sulfide with benzyl chloride followed by exchange of the counter anion (Cl^?) with SbF^?₆ ( 2a ), PF^?₆ ( 2b ), or BF^?₄ ( 2c ). In the bulk polymerization of glycidyl phenyl ether (PGE) with 2 , initiator activity of the sulfonium salts was evaluated by comparison with that of benzyl tetramethylenesulfonium hexafluoroantimonate ( 1 , R = H). Among the initiators, 2a showed the highest activity, and was much more active than 1 (R = H). Since the polymerization of PGE with 2a proceeded efficiently at more than 80°C but not at all at less than 60°C, 2a was suggested to be a good latent thermal initiator.