Effects of Dye‐Adsorption Solvent on the Performances of the Dye‐Sensitized Solar Cells Based on Black Dye

The effects of the dye‐adsorption solvent on the performances of the dye‐sensitized solar cells (DSSCs) based on black dye have been investigated. The highest conversion efficiency (10.6 %) was obtained in the cases for which 1‐PrOH and the mixed solvent of EtOH and tBuOH (3:1 v/v) were employed as dye‐adsorption solvents. The optimized value for the dielectric constant of the dye‐adsorption solvent was found to be around 20. The DSSCs that used MeOH as a dye‐adsorption solvent showed inferior solar‐cell performance relative to the DSSCs that used EtOH, 1‐PrOH, 2‐PrOH, and 1‐BuOH. Photo‐ and electrochemical measurements of black dye both in solution and adsorbed onto the TiO₂ surface revealed that black dye aggregates at the TiO₂ surface during the adsorption process in the case for MeOH. Both the shorter electron lifetime in the TiO₂ photoelectrode and the greater resistance in the TiO₂–dye–elecrolyte interface, attributed to the dye aggregation at the TiO₂ surface, cause the decrease in the solar‐cell performance of the DSSC that used MeOH as a dye adsorption solvent.     

A dual catalyst system provides the shortest pathway for L-menthol synthesis

We have demonstrated that a combination of enantiopure 2-diarylmethylpyrrolidines and heterogeneous Pd/BaSO(4) is an efficient catalytic system for the asymmetric hydrogenation of citral, specifically, a mixture of E-citral and Z-citral in any ratio, and that citronellal is obtained with high enantioselectivity. This dual catalyst system provides a new and more economical route to L-menthol.     

Tin oxide-surface modified anatase titanium(IV) dioxide with enhanced UV-light photocatalytic activity

[Sn(acac)(2)]Cl(2) is chemisorbed on the surfaces of anatase TiO(2)via ion-exchange between the complex ions and H(+) released from the surface Ti-OH groups without liberation of the acetylacetonate ligand (Sn(acac)(2)/TiO(2)). The post-heating at 873 K in air forms tin oxide species on the TiO(2) surface in a highly dispersed state on a molecular scale ((SnO(2))(m)/TiO(2)). A low level of this p block metal oxide surface modification (~0.007 Sn ions nm(-2)) accelerates the UV-light-activities for the liquid- and gas-phase reactions, whereas in contrast to the surface modification with d block metal oxides such as FeO(x) and NiO, no visible-light response is induced. Electrochemical measurements and first principles density functional theory (DFT) calculations for (SnO(2))(m)/TiO(2) model clusters (m = 1, 2) indicate that the bulk (TiO(2))-to-surface interfacial electron transfer (BS-IET) enhances charge separation and the following electron transfer to O(2) to increase the photocatalytic activity.     

Diffusion of ammonium ions in [(NH4)1−xRbx]3H(SO4)2 studied by 1H spin–lattice relaxation in the rotating frame

Translational diffusion of NH₄⁺ ions in [(NH₄)_1?xRb_x]₃H(SO₄)₂ has been evaluated quantitatively by means of ¹H spin–lattice relaxation times in the rotating frame, T_1ρ. In the high-temperature phase (phase I), the mean residence times of NH₄⁺ ions are three or four orders of magnitude larger than those of the acidic protons. In the room-temperature phase (phase II), they are two or three orders of magnitude larger than those of the acidic protons. The transition from phases II to I causes one order of magnitude enhancement in the diffusion of NH₄⁺ ions. The mean residence time of NH₄⁺ ions increases with increase in the Rb content. The similar trend is also observed in phase II.     

Rhenium-catalyzed regio- and stereoselective addition of two carbon units to terminal alkynes via carbon-carbon bond cleavage of β-keto sulfones

Treatment of β-keto sulfones with terminal alkynes gave unsaturated δ-keto sulfones in good to excellent yields under rhenium catalysis. In this reaction, the insertion of the alkynes into the nonstrained carbon-carbon single bond between the α- and β-positions of the β-keto sulfones proceeded smoothly, and (Z)-isomers were produced with high regio- and stereoselectivities.     

A new interpretation of the Shimura curve with discriminant 6 in terms of Picard modular forms

In this paper we give a realization of the Shimura curve for the quaternion algebra over Q with discriminant 6 as a quotient space of the complex upper half plane by the triangle group Δ(3, 6, 6). It is given by the Schwarz map for the Gauss hypergeometric differential equation E(\frac16,\frac13,\frac23){E\left(\frac{1}{6},\frac{1}{3},\frac{2}{3}\right)}. The corresponding abelian surfaces are obtained as isogenous components of the Jacobi varieties of the Picard curves C(s): w³=z(z-1) (z-\frac12 (1-s))(z-\frac12 (1+s)){C(s): w^3=z(z-1)\break \left(z-\frac{1}{2} (1-s)\right)\left(z-\frac{1}{2} (1+s)\right)}.     

Roots of Ehrhart polynomials arising from graphs

Several polytopes arise from finite graphs. For edge and symmetric edge polytopes, in particular, exhaustive computation of the Ehrhart polynomials not merely supports the conjecture of Beck et al. that all roots α of Ehrhart polynomials of polytopes of dimension D satisfy −D≤Re(α)≤D−1, but also reveals some interesting phenomena for each type of polytope. Here we present two new conjectures: (1) the roots of the Ehrhart polynomial of an edge polytope for a complete multipartite graph of order d lie in the circle |z+\fracd4| ￡ \fracd4|z+\frac{d}{4}| \le \frac{d}{4} or are negative integers, and (2) a Gorenstein Fano polytope of dimension D has the roots of its Ehrhart polynomial in the narrower strip -\fracD2 ￡ Re(a) ￡ \fracD2-1-\frac{D}{2} \leq \mathrm{Re}(\alpha) \leq \frac{D}{2}-1. Some rigorous results to support them are obtained as well as for the original conjecture. The root distribution of Ehrhart polynomials of each type of polytope is plotted in figures.     

Decomposition Mechanism of Fluorinated Compounds in Water Plasmas Generated Under Atmospheric Pressure

Decomposition mechanism of HFC-134a, HFC-32, and CF₄ in water plasmas at atmospheric pressure has been investigated. The decomposition efficiency of 99.9% can be obtained up to 3.17 mol kWh⁻¹ of the ratio of hydrofluorocarbon (HFC) feed rate to the arc power and 1.89 mol kWh⁻¹ of the ratio of perfluorocarbon (PFC) feed rate to the arc power. The species such as H₂, CO, CO₂, CH₄, and CF₄ were detected from the effluent gas of both PFC and HFC decomposition. However, CH₂F₂ and CHF₃ were observed only in the case of HFC decomposition. The HFC and PFC decomposition generate CH₂F, CHF_{x (x:1–2)}, and CF_{y (y:1–3)} radicals, then those radicals were subsequently oxidized by oxygen, leading to CO and CO₂ generation in the excess oxygen condition. However, when there is insufficient oxygen available, those radicals were easily recombined with fluorine to form by-product such as CH₂F₂, CHF₃, and CF₄.     

The Symplectic Deligne–Mumford Stack Associated to a Stacky Polytope

We discuss a symplectic counterpart of the theory of stacky fans. First, we define a stacky polytope and construct the symplectic Deligne–Mumford stack associated to the stacky polytope. Then we establish a relation between stacky polytopes and stacky fans: the stack associated to a stacky polytope is equivalent to the stack associated to a stacky fan if the stacky fan corresponds to the stacky polytope.     

Synthesis of both enantiomers of conosilane A

Conosilane A, an inhibitor of 11β-hydroxysteroid dehydrogenase type 1 isolated from Conocybe siliginea, is a tremulane sesquiterpene with highly oxygenated tetracyclic ring system. In this study, we report the synthesis of both enantiomers of conosilane A. The key steps of this synthesis involve asymmetric aldol reaction, furan-ring oxidation followed by transacetalization and intramolecular reductive Heck-type cyclization.