Novel soft chemical method for optically transparent Ru(bpy)3-K4Nb6O17 thin film

A unique guest-guest ion exchange method was developed for preparing a thin film of a nano-layered K(4)Nb(6)O(17).3H(2)O that possesses both (1) optical transparency and (2) ion-exchangeability under ambient conditions without calcination at high temperature. An optically transparent Ru(bpy)(3)(2+)-K(4)Nb(6)O(17) hybrid thin film, a photoresponsive electrode, was successfully prepared by the guest-guest exchange method by use of the intercalation compound MV(2+)-K(4)Nb(6)O(17) as a precursor. The optically transparent Ru(bpy)(3)(2+)-K(4)Nb(6)O(17) hybrid thin films have been characterized by X-ray diffraction, SEM, AFM, IR, and UV spectroscopies, as well as elemental analysis. The electrochemical behavior of the ITO/Ru(bpy)(3)(2+)-K(4)Nb(6)O(17) hybrid thin film electrode was studied; it also exhibits swift photoresponse in the visible region.     

Platinum(II)-catalyzed reaction of 2-alkynylbenzoates or benzothioates with vinyl ethers: a concise method for synthesis of 1-acyl-4-alkoxy- or 1-acyl-4-alkylsulfanylnaphthalene derivatives

[reaction: see text] A concise method for the preparation of 1-acyl-4-alkoxy- or 1-acyl-4-alkylsulfanylnaphthalenes has been developed by the reaction of o-ethynylbenzoates or benzothioates with vinyl ethers, in the presence of a catalytic amount of PtCl(2). It is proposed that the reaction proceeds through [3 + 2]-cycloaddition of the platinum-containing carbonyl ylides followed by 1,2-alkyl migration.     

Elastic friction drive of surface acoustic wave motor

Importance of elastic deformation control to obtain large output force with a surface acoustic wave (SAW) motor is discussed in this paper. By adding pre-load to slider, stator and slider surfaces are deformed in a few tens nanometer. Appropriate deformation in normal direction against normal vibration displacement amplitude of SAW existed. By moderate deformation, the output force of the SAW motor was enlarged up to about 10 N and no-load speed was 0.7 m/s. To produce this performance, the transducer weight and slider size were only 4.2 g and 4 x 4 mm(2).By traveling wave propagation, surface particles of the SAW device move in elliptical motion. Due to the amplitude of the elliptical motion is 10 or 20 nm order, the contact condition of the slider is very critical. To control the contact condition, namely, the elastic deformation of the slider and stator surface in nanometer order, a lot of projections were fabricated on the slider surface. The projection diameter was 20 micro m. In static condition, the elastic deformation and stress were evaluated with the FEM analysis. From this calculation and the simulation result, it is consider that the wave crest is distorted, hence the elasticity has influence on the friction drive condition.Elastic deformation of the stator surface beneath the projection from the initial position were evaluated. In 4 x 4 mm(2) square area, the sliders had from 1089 to 23,409 projections. Depression was independent to the contact pressure. However, the output force depended on the depression although the projection density were different. From the view point of the output power of the motor, the proper depression was independent to the projection density. Around 25 nm depression, the output force and output power were maximized. This depression value was almost same as the vibration displacement amplitude of the stator transducer.     

Reversible light-driven structural changes between the mono- and bilayer stacking alignments in 4-octadecyloxystilbazolium arylcarboxylate films

The present investigation deals with the light-driven morphological changes in multilamella films of N-methyl-4-octadecyloxystilbazolium arylcarboxylates (C18OStz+X-) cast on glass slides. The results of XRD analysis show a photostimulated layer expansion and shrinkage of the stacked thin films along the c-axis under alternative illumination at >350 and 254 nm, respectively. It was revealed that such lamellar changes could be switched either way by a reversible transformation between the mono- and bilayer units in these stacked multilamella films. Moreover, such controlled structural adjustments in the alignment could be initiated by the photocyclodimerization of the stilbazolium moieties of the arylcarboxylate salts; i.e., a monolayer-to-bilayer transformation could be induced at a stage of only 10% cyclodimer formation. The photoinduced patterning on the surface of the films was also analyzed by SEM and fluorescence microscopic investigations.     

Oxidation of sec‐alcohols with Ru(II)‐bearing microgel star polymer catalysts via hydrogen transfer reaction: Unique microgel‐core catalysis

Oxidation of sec‐alcohols was investigated with ruthenium‐bearing microgel core star polymer catalysts [Ru(II)‐Star]. The star polymer catalysts were directly prepared via RuCl₂(PPh₃)₃‐catalyzed living radical polymerization of methyl methacrylate (MMA), followed by the arm‐linking reaction with ethylene glycol dimethacrylate ( 1 ) in the presence of diphenylphosphinostyrene ( 2 ). The Ru(II)‐Star efficiently and homogeneously catalyzed the oxidation of 1‐phenylethanol ( S1 ) to give a corresponding ketone (acetophenone) in higher yield (92%) than the analogs of polymer‐supported ruthenium complexes. Importantly, the star catalyst afforded high recycling efficiency in the oxidation. They held catalytic activity against three times catalysis even though they were recovered under air‐exposure, whereas the conventional RuCl₂(PPh₃)₃ lost the activity for same recycling procedure due to the deactivation by oxygen. The stability of the star catalysts during the recycle experiment was confirmed by detailed spectroscopic characterization. The star polymers also catalyzed oxidation for a wide range of sec‐alcohols with aromatic and aliphatic groups. The substrate affinity was different from that with RuCl₂(PPh₃)₃, suggesting the unique selectivity caused by the specific structure. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.     

A function space model approach to the rational evaluation subgroups

Let f : U → X be a map from a connected nilpotent space U to a connected rational space X. The evaluation subgroup G _*(U, X; f), which is a generalization of the Gottlieb group of X, is investigated. The key device for the study is an explicit Sullivan model for the connected component containing f of the function space of maps from U to X, which is derived from the general theory of such a model due to Brown and Szczarba (Trans Am Math Soc 349, 4931–4951, 1997). In particular, we show that non Gottlieb elements are detected by analyzing a Sullivan model for the map f and by looking at non-triviality of higher order Whitehead products in the homotopy group of X. The Gottlieb triviality of a fibration in the sense of Lupton and Smith (The evaluation subgroup of a fibre inclusion, 2006) is also discussed from the function space model point of view. Moreover, we proceed to consideration of the evaluation subgroup of the fundamental group of a nilpotent space. In consequence, the first Gottlieb group of the total space of each S ¹-bundle over the n-dimensional torus is determined explicitly in the non-rational case.      

Dynamic Vapochromic Behaviors of Organic Crystals Based on the Open–Close Motions of S‐Shaped Donor–Acceptor Folding Units

The first vapochromic organic crystals are described with respect to their preparation, color change, adsorption/desorption properties, crystal structures, and color‐change mechanism. Non‐solvatochromic, 1,4,5,8‐naphthalene‐tetracarboxylic diimide (NDI) derivatives 1 a bearing two pyrrole imine (PI) tethers have been used as a motif for the crystal packing template. Red‐purple vapochromic solid 3 was prepared by evacuation of orange crystals 2 (equivalent to 1 a ?2 MeOH), obtained by recrystallization of 1 a from MeOH. Solid 3 showed high‐adsorption ability and unprecedented vapor‐dependent color changes upon exposure to a variety of organic vapors, whereas light brown amorphous solid 1 a , did not show vapo‐ or solvatochromic behavior toward any organic solvent. The strong adsorption capability of 3 was confirmed by TGA experiments and adsorption/desorption isotherms. Analysis of the solid‐state UV/Vis analysis revealed that the vapor‐dependent color changes of 3 were owed to the specific interference of solvent vapors with its broad CT absorbance at λ=450–650 nm. Packing structures of 1 a in orange crystals 2 , red‐purple solid 3 , and regenerated orange solid 2 were unequivocally established by single crystal and synchrotron powder X‐ray diffraction, respectively. Molecular structures and arrays of 1 a in these materials indicated that 1) unit 1 a had an S‐shaped folded conformation in 2 and 3 by intramolecular donor–acceptor interactions between NDI and two PI units; 2) inclusion of the guest vapor into the S‐shaped template decreased the intramolecular PI‐NDI interactions, accompanied by increasing intermolecular NDI‐NDI and PI‐PI interactions; and 3) such flexible, open–close motions of the S‐shaped template could be repeated during reversible adsorption/desorption processes without degradation of crystal packing. The adsorption properties and mechanism of molecular shape‐dependent vapochromic behavior of 3 are discussed with reference to experimental results, crystallographic data, and theoretical calculations.     

Dynamic properties of combustion instability in a lean premixed gas-turbine combustor

We experimentally investigate the dynamic behavior of the combustion instability in a lean premixed gas-turbine combustor from the viewpoint of nonlinear dynamics. A nonlinear time series analysis in combination with a surrogate data method clearly reveals that as the equivalence ratio increases, the dynamic behavior of the combustion instability undergoes a significant transition from stochastic fluctuation to periodic oscillation through low-dimensional chaotic oscillation. We also show that a nonlinear forecasting method is useful for predicting the short-term dynamic behavior of the combustion instability in a lean premixed gas-turbine combustor, which has not been addressed in the fields of combustion science and physics.