Effects of crown ether on hydrogenation over nickel and cobalt boride catalysts: effects in catalyst preparation and effects as additives

The nickel and cobalt boride catalysts prepared in the presence of crown ethers show different selectivities from the ordinary boride catalysts in the reduction of cycloalkene, styrene oxide, and 4-t-butylcyclohexanone.     

Diversification of self-organized architectures in supramolecular dye assemblies

Upon complexation with bismelamine receptors (BMn) featuring different alkyl linker lengths (number of methylene groups (n) = 5-12), a barbituric acid merocyanine dye (1) can be loaded into diverse self-organized superstructures through multiple hydrogen-bonding interactions. UV/vis, dynamic light scattering, and NMR studies in cyclohexane demonstrate that the diversification of the primarily formed hydrogen-bonded species in solution occurs by varying the linker length of BMn. Hierarchical organization of the hydrogen-bonded species is achieved by slow evaporation of the solvent (forming solvent-free films), and the resulting superstructures are evaluated by polarized optical microscopy, X-ray diffraction, SEM, and AFM techniques. The formation of columnar structures with and without two-dimensional ordering are revealed for shorter (n = 5-7) and longer (n = 11, 12) linker bis(melamines), respectively. On the contrary, in the cases of n = 8-10, the formation of lamellar structures is unveiled. Several assemblies (n = 5, 7, 11) indicate the formation of a liquid crystalline mesophase in POM and DSC analyses. Hierarchical organization is also achieved in solution by prolonged aging, affording phase-separated crystalline nanofibers (n = 5, 7) and soft nanofibrils agglomerating into wormlike objects (n = 8), gel-forming continuous globular networks (n = 10), and nanofibers (n = 11, 12). These superstructural and morphological diversifications are an outcome of the variation in the primarily formed hydrogen-bonded supramolecular architectures. Using this strategy, diverse self-assembled materials will be obtained from a single dye component.     

PHOTORESPONSIVE ARTIFICIAL MEMBRANE. REGULATION OF MEMBRANE PERMEABILITY OF LIPOSOMAL MEMBRANE BY PHOTOREVERSIBLE CIS-TRANS ISOMERIZATION OF AZOBENZENES

Abstract— Photoresponsive artificial membranes have been prepared by embedding amphiphatic alkyl-ammonium salts containing azobenzene chromophore in dipalmitoylphosphatidylcholine liposomes. The configurational change due to trans→cis photoisomerization of the azobenzene chromophore provided the perturbation of the membrane structure to result in the increase of the water and bromo-thymol blue permeability of the liposomal membranes.     

On the number of disjoint convex quadrilaterals for a planar point set

For a given planar point set P, consider a partition of P into disjoint convex polygons. In this paper, we estimate the maximum number of convex quadrilaterals in all partitions.     

Defect structure analysis of B-site doped perovskite-type proton conducting oxide BaCeO3 Part 1: The defect concentration of BaCe0.9M0.1O3−δ (M = Y and Yb)

By means of a high-temperature gravimetry, the defect chemical relationships between oxygen nonstoichiometry and water content in BaCe_0.9M_0.1O_3?δ (M = Y and Yb) were investigated as functions of partial pressure of oxygen, P(O₂), partial pressure of water vapor, P(H₂O), and temperature. Concentrations of protonic defect and that of oxygen vacancy strongly depend on P(H₂O) and temperature, while the dependences on P(O₂) were weak. The equilibrium constants of the water vapor incorporation reaction H₂O + V_O^??? + O_O^× = 2OH_O^? were determined. Concentrations of hole, [h^?], in the dry-atmospheres were determined by the weight gain by the incorporation of oxygen from the gas atmospheres. The [h^?] values increased with decreasing temperature. The [h^?] values were estimated to be about 2 to 3 orders of magnitude less than [OH_O^?] values measured in the wet-atmospheres.     

Galvanomagnetic properties of air-stable and highly conductive potassium-intercalated graphite sheet

Magnetoresistance and Hall coefficient of air-stable potassium-intercalated graphite sheets (hereafter abbreviated as K-PGS) were determined at room temperature. The magnitude of the magnetoresistance and the absolute value of Hall coefficient of K-PGS decreased with increasing potassium content of K-PGS, n_K/n_C. Two-carrier model was used for calculating carrier density and mobility. The electron density increased with increasing n_K/n_C: 3.07×10²⁰ cm⁻³ (n_K/n_C=0.005), 5.67×10²⁰ cm⁻³ (n_K/n_C=0.008) and 6.40×10²⁰ cm⁻³ (n_K/n_C=0.011). The value of the electron density of K-PGS with n_K/n_C=0.011 (nominal composition KC₉₁) was about 80% of the reported value, 7.8×10²⁰ cm⁻³, for KC₄₈ (n_K/n_C=0.021) prepared from HOPG (highly oriented pyrolytic graphite). The mobility decreased with increasing n_K/n_C: 2.11×10³ cm² V⁻¹ s⁻¹ (n_K/n_C=0.005), 1.42×10³ cm² V⁻¹ s⁻¹ (n_K/n_C=0.008) and 1.34×10³ cm² V⁻¹ s⁻¹ (n_K/n_C=0.011). The value of the mobility of K-PGS with n_K/n_C=0.011 was about 60% of the reported value (2300 cm² V⁻¹ s⁻¹) for KC₄₈ prepared from HOPG.     

Relationship between adsorbed fibronectin and cell adhesion on a honeycomb-patterned film

Substratum surface morphology plays a vital roles in cellular behavior. Here, we characterized adsorption of fibronectin (Fn) as a typical cell adhesion protein onto honeycomb-patterned films made of poly(ε-caprolactone) (PCL) by using atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM). In order to determine how cells adhere to a honeycomb-patterned film, focal adhesion of cardiac myocytes (CMYs) and endothelial cells (ECs) on the films were studied by using fluorescence labeling of vinculin. Fn adsorbs around the pore edges to form ring-shaped structures. CMYs and ECs adhere onto the honeycomb-patterned films at focal contact points localized around pore edges distributed over the entire cellular surface. The focal contact points on the honeycomb-patterned films correspond well with the adsorption sites of Fn. We suggest that the cell response to honeycomb-patterned films is associated with the adsorption pattern of Fn on the film.     

Three-variable reversible Gray-Scott model

Even though the field of nonequilibrium thermodynamics has been popular and its importance has been suggested by Demirel and Sandler [J. Phys. Chem. B 108, 31 (2004)], there are only a few investigations of reaction-diffusion systems from the aspect of thermodynamics. A possible reason is that model equations are complicated and difficult to analyze because the corresponding chemical reactions need to be reversible for thermodynamical calculations. Here, we introduce a simple model for calculation of entropy production rate: a three-variable reversible Gray-Scott model. The rate of entropy production in self-replicating pattern formation is calculated, and the results are compared with those reported based on the Brusselator model in the context of biological cell division.     

High-yield preparation of uniform cobalt hydroxide and oxide nanoplatelets and their characterization

Cobalt hydroxide nanoplatelets with a uniform hexagonal shape were prepared in high yield ( approximately 95%) by a facile hydrothermal route in the presence of poly(vinylpyrrolidone). This method provides a simple, low-cost, and large-scale route to produce beta-cobalt hydroxide nanoplatelets with an average diameter of 280 nm and a thickness of ca. 26 nm which show a predominant well-crystalline hexagonal brucite-like phase. Their thermal decomposition produced anisotropic nanoplatelets of cobalt oxides (CoO and Co3O4) under designed temperatures. The products were characterized by transmission electronic microscopy, selected-area electron diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetric, and thermogravimetric analysis. The magnetic properties of the products were investigated by a superconducting quantum interference device magnetometer. Co3O4 nanoplatelets exhibit a superparamagnetic behavior, and they might be a promising material to study the magnetic tunneling effect as anisotropic nanostructures.