Stepwise pattern modification of neuronal network in photo-thermally-etched agarose architecture on multi-electrode array chip for individual-cell-based electrophysiological measurement

We have developed a procedure for stepwise topographical control of network patterns and neurite connection directions between adjacent living neurons using an individual-cell-based on-chip multi-electrode array (MEA) cell cultivation system with an agarose microchamber (AMC) array. This procedure enables flexible and precise control of the cell positions and easy and flexible control of the pattern modification of connections between the cells in AMCs through stepwise photo-thermal etching in which a portion of the agarose layer on the chip is melted with a 1480 nm infrared laser beam even during cultivation. With adequate laser power and this stepwise procedure, we can fabricate narrow micrometer-order grooves (microchannels) during cultivation in a stepwise manner. Using this procedure, we controlled the direction of elongation of axons and dendrites selectively and confirmed the direction by immunostaining. We also demonstrated electrophysiological one-way transmission of signals among aligned hippocampal neurons in which the directions of the neurite connections were controlled using this stepwise photo-thermal etching procedure. These results demonstrate the potential of full direction control of neurite connections between neurons using stepwise photo-thermal etching to form microchannels one by one in an on-chip AMC/MEA cell cultivation system. We can thus better understand the meaning of neuronal network patterns and connection directions.     

Design of controlled release system with multi-layers of powder

Pellets containing active ingredients were coated with water-insoluble powders, i.e. hydrogenated caster oil (Lubliwax (WAX)) and magnesium stearate (Mg-St). The influences of the structural difference of the sustained release layer and curing conditions on the drug release rate were investigated. Sodium valproate (VP-Na) was used as a highly water-soluble model drug. Drug release profiles were influenced by the combination of the WAX layer and the Mg-St layer. Even if the formula of sustained release layers were the same, drug release rate could be affected by the structural difference of the controlled release layer. The Mg-St layer was more effective in prolonging drug release than the WAX layer. Compared with single and double layer types, the triple layer (sandwich) type was most effective in obtaining a long sustained drug release. Heat-treatment retarded drug release mainly by increasing the density of the sustained release layer of the WAX. The Mg-St was effective in protecting the agglomeration between particles during heat-treatment. Optimal heat-treatment conditions were found to exist. Scanning electron microscopy (SEM) analysis indicated that heat-treatment caused the WAX to melt, formed a film-like structure and made the release layer dense. Furthermore, heat-treatment changed the release pattern of VP-Na from sustained release pellets with a multi-layer of powder, leading to zero-order release.     

Symplectic Toric Space Associated to Triangle Inequalities

Let M _n be the moduli space of spatial polygons with n edges. An open dense subset of M _n admits a T ^n–3 -action, although this action does not extend to M _n . The action together with a symplectic structure on M _n naturally defines a convex polytope _n in ^n–3. In this paper, from M _n , we construct a singular symplectic toric manifold with _n as the image of the moment map.     

An FeIII wheel with a zwitterionic ligand: the structure and magnetic properties of [Fe(OMe)2(proline)]12[ClO4]12

The structure and magnetic properties of a dodecanuclear iron(III) wheel are reported, featuring a bridging zwitterionic ligand.     

Controlling the spontaneous emission rate of single quantum dots in a two-dimensional photonic crystal

We observe large spontaneous emission rate modification of individual InAs quantum dots (QDs) in a 2D photonic crystal with a modified, high-Q single-defect cavity. Compared to QDs in a bulk semiconductor, QDs that are resonant with the cavity show an emission rate increase of up to a factor of 8. In contrast, off-resonant QDs indicate up to fivefold rate quenching as the local density of optical states is diminished in the photonic crystal. In both cases, we demonstrate photon antibunching, showing that the structure represents an on-demand single photon source with a pulse duration from 210 ps to 8 ns. We explain the suppression of QD emission rate using finite difference time domain simulations and find good agreement with experiment.     

Mössbauer study of ultrafine FeF2 particles

Ultrafine antiferromagnetic FeF₂ particles (<10 nm) were prepared by a new technique, viz, the SF₆-sensitized infrared photodecomposition of Fe(CO)₅ induced by a transversely excited atmospheric (TEA) CO₂ laser. The magnetic properties have been examined by⁵⁷Fe Mössbauer spectroscopy. At low temperatures the magnetic hyperfine field decreases faster with increasing temperature than the hyperfine field of the bulk; this behavior appears to be consistent with collective magnetic excitations. The transition between the paramagnetic and antiferromagnetic states takes place at a higher temperature and over a broader range as compared to the bulk. FeF₂ ultrafine particles are relatively sensitive to oxidation; cubic-type iron oxide is formed.     

Coordination complex between haemin and parallel-quadruplexed d(TTAGGG)

Haemin, iron(III)-protoporphyrin IX complex, and parallel-quadruplexed d(TTAGGG) have been shown to form a stable coordination complex which exhibits spectroscopic properties remarkably similar to those of haemoproteins.     

Room temperature molten fluorometallates: 1-ethyl-3-methylimidazolium hexafluoroniobate(V) and hexafluorotantalate(V)

The first room temperature molten salts containing hexafluorometallate anions of transition metals, 1-ethyl-3-methylimidazolium (EMIm) hexafluoroniobate, EMImNb(V)F₆, and hexafluorotantalate, EMImTa(V)F₆, have been synthesized by the reactions of EMImF·2.3HF with NbF₅ and TaF₅, respectively. They exhibit similar physical properties. Viscosities and conductivities are 49 cP and 8.5 mS cm⁻¹ for EMImNbF₆ and 51 cP and 7.1 mS cm⁻¹ for EMImTaF₆, respectively at 298 K.     

A vector processing algorithm of auxiliary integral evaluation for two-electron Gaussian integrals

A six-term auxiliary integral expression for the two-electron Gaussian integral is derived on the basis of the Chebyshev polynomial approximation instead of the seven-term Taylor expansion. This expression and the related recurrence formula enable us to perform a high-speed calculation on a vector processing computer.