Dye-sensitized solar cells based on donor-π-acceptor fluorescent dyes with a pyridine ring as an electron-withdrawing-injecting anchoring group

A new‐type of donor–acceptor π‐conjugated (D‐π‐A) fluorescent dyes NI3 – NI8 with a pyridine ring as electron‐withdrawing‐injecting anchoring group have been developed and their photovoltaic performances in dye‐sensitized solar cells (DSSCs) are investigated. The short‐circuit photocurrent densities and solar energy‐to‐electricity conversion yields of DSSCs based on NI3 – NI8 are greater than those for the conventional D‐π‐A dye sensitizers NI1 and NI2 with a carboxyl group as the electron‐withdrawing anchoring group. The IR spectra of NI3 – NI8 adsorbed on TiO₂ indicate the formation of coordinate bonds between the pyridine ring of dyes NI3 – NI8 and the Lewis acid sites (exposed Tiⁿ⁺ cations) of the TiO₂ surface. This work demonstrates that the pyridine rings of D‐π‐A dye sensitizers that form a coordinate bond with the Lewis acid site of a TiO₂ surface are promising candidates as not only electron‐withdrawing anchoring group but also electron‐injecting group, rather than the carboxyl groups of the conventional D‐π‐A dye sensitizers that form an ester linkage with the Brønsted acid sites of the TiO₂ surface.     

The [2?+?2?+?2] mechanisms of trimerization of three ethynes and monosilaethylenes

The mechanisms of [2?+?2?+?2] reactions of three ethynes and monosilaethylenes to form benzene and 1,3,5-trisilacyclohexane were studied by ab initio MO methods. The reaction mechanisms were analyzed by configuration interaction/localized molecular orbital/CASSCF calculations. Although the [2?+?2?+?2] reaction of ethyne is typically ??homologous?? concerted, that of monosilaethylene is polarized (ionic-cyclic) one-step reaction. In addition, the aromaticity along the intrinsic reaction coordinate pathway was studied using the index of deviation from aromaticity. Although the transition state of trimerization of ethyne does not have an aromatic nature for the ??- and ??-bonds formation system, the crossing point of the ??-bond formation and ??-bond breaking shows an aromatic nature.     

Melting Point Elevation of Isotactic Polypropylene

The melting point of a conventional isotactic polypropylene (PP) was enhanced by a rapid annealing procedure of an extruded sheet composed of β trigonal form crystals having thick lamellae, which was prepared by T-die processing with a specific β-nucleating agent, N,N′-dicyclohexyl-2,6-naphthalenedicarboxamide. Although the melting point of PP with α monoclinic form, prepared by a conventional processing method, is known to be located around at 165°C, the sample obtained by the present technique showed a higher melting point, 170°C. The phase transformation from β-to α-form crystals, retaining the lamellar thickness, was responsible for the melting point elevation.     

Fast Calculation of Computer-Generated Fresnel Hologram Utilizing Distributed Parallel Processing and Array Operation

Fresnel CGH for a three-dimensional (3-D) object is generated by calculating the Fresnel diffraction, but it requires a huge amount of calculation. This is one reason for the difficulty in realizing real-time holography. We propose fast calculation method of computer-generated Fresnel hologram (Fresnel CGH) utilizing distributed parallel processing and array operation. In our method, a projected image with depth information of the 3-D object is prepared to calculate the Fresnel diffraction. The Fresnel diffraction of the projected image is then calculated with depth information by array operation and distributed parallel processing. Parallel processing is realized using JavaSpaces and many standard computers. In our array operation, calculation error in phase distribution on a hologram occurs more than the strict Fresnel diffraction. However, it was confirmed by experiments that the influence of an error can be controlled and ignored. In this paper, our proposed method and some experimental results are shown.     

Improvement in reliability of probabilistic test of significant differences in GeneChip experiments.

A probabilistic test (FUMI theory) for GeneChip experiments has been proposed for selecting the genes which show significant differences in the gene expression levels between a single pair of treatment and control. This paper describes that the reliability of the judgment by the FUMI theory can be enhanced, when the selected genes are referred to biomolecular-functional networks of a commercial database. The genes judged as being differently expressed are grouped into a cluster in the biomolecular networks. It is also demonstrated that false positive genes have a trend in the networks to be isolated from each other, and also away from the clustered genes, since the false positive genes are randomly selected.     

Theoretical analysis of concerted and stepwise mechanisms of the hetero-Diels–Alder reaction of butadiene with formaldehyde and thioformaldehyde

The concerted and stepwise mechanisms of the hetero-Diels–Alder reaction of butadiene with formaldehyde and thioformaldehyde were studied by a CASSCF molecular orbital method. The energy barrier of the concerted reaction of butadiene with formaldehyde is about 21 kcal/mol higher than that of butadiene with thioformaldehyde at the CAS-MP2 calculation level. For the stepwise reaction paths, the energy barrier for the first step process of the reaction of butadiene with formaldehyde is about 17 kcal/mol above that of butadiene with thioformaldehyde. The concerted pathways for both systems are more favorable by 9–12 kcal/mol than the stepwise pathways. The electronic mechanisms for the concerted reactions of both reaction systems are also discussed by a CiLC analysis.     

Determination of rat brain kynurenic acid by column-switching HPLC with fluorescence detection

Kynurenic acid (KYNA), one of the tryptophan metabolites, serves as an endogenous antagonist of N-methyl-d-aspartate and the alpha7 nicotinic receptors in mammalian brains. In the present study, the column-switching high-performance liquid chromatography (HPLC) method we developed for plasma KYNA was extended and validated for the determination of brain KYNA. Rat cerebrum, cerebellum and brainstem homogenates were deproteinized with acetone, and the extracts reconstituted with the mobile phase were injected onto the HPLC. In spite of the facile pretreatment, the fluorescence peak of KYNA in the cerebrum, cerebellum and brainstem was clearly observed with no interfering peaks. Intra- and inter-day precisions [relative standard deviation (%)] and accuracies [relative mean error (%)] were satisfactory (< +/-5.8%). The concentrations of KYNA in rat cerebrum, cerebellum, and brainstem were 224 +/- 65.8, 606 +/- 191, and 323 +/- 114 fmol/mg protein (n = 5), respectively. The proposed HPLC method will be a useful tool for pharmacokinetic and pharmacological researches on brain KYNA.     

Significance of water quality and radiation wavelength for UV photolysis of PhCs in simulated mixed solutions

Ultraviolet (UV) photolysis of sixteen pharmaceutical compounds (PhCs) in mixed solutions with four types of water and two sets of UV radiation was investigated. UVC (254 nm) photolysis was ineffective at eliminating a large number of PhCs while a big number of them were refractory. However, vacuum UV (VUV: 185 nm + 254 nm) photolysis in the same experimental conditions eliminated the PhCs almost completely. The eliminations in ultrapure water (UPW), tap water (TW) and Neya River water (NRW) and their organic/inorganic contents were inversely correlated, which was more evident in VUV photolysis. Natural organic matter (NOM) in NRW did not have an impact in indirect photolysis, but effluent organic matter (EfOM) in secondary-treated effluent (NWTPE) enhanced indirect photolysis, which was more evident in VUV photolysis underlining the point that radiation wavelength/intensity can be a limiting factor in organic-rich waters. Moreover, VUV photolysis was far superior (90% mineralization) to UVC photolysis (10% mineralization) for PhCs mineralization. The greatly enhanced elimination and mineralization efficiencies observed for VUV photolysis were attributed to accelerated direct photolysis with 185 nm wavelength and indirect photolysis involving ^·OH. The results demonstrated efficacy of VUV photolysis in wastewater treatment and its potential use as a tertiary treatment.      

Nitrogen fixation catalyzed by ferrocene-substituted dinitrogen-bridged dimolybdenum–dinitrogen complexes: unique behavior of ferrocene moiety as redox active site

A series of dinitrogen-bridged dimolybdenum–dinitrogen complexes bearing metallocene-substituted PNP-pincer ligands is synthesized by the reduction of the corresponding monomeric molybdenum–trichloride complexes under 1 atm of molecular dinitrogen. Introduction of ferrocene as a redox-active moiety to the pyridine ring of the PNP-pincer ligand increases the catalytic activity for the formation of ammonia from molecular dinitrogen, up to 45 equiv. of ammonia being formed based on the catalyst (22 equiv. of ammonia based on each molybdenum atom of the catalyst). The time profile for the catalytic reaction reveals that the presence of the ferrocene unit in the catalyst increases the rate of ammonia formation. Electrochemical measurement and theoretical studies indicate that an interaction between the Fe atom of the ferrocene moiety and the Mo atom in the catalyst may play an important role to achieve a high catalytic activity.     

Theoretical study on the reaction mechanisms of ethylene with Cp2TiR, Cp2Ti(Cl)R, and Cp2Ti(Cl:AlH2Cl)R (R=H and CH3)

The potential energy surfaces for reactions of ethylene with Cp₂Ti⁺R, Cp₂Ti(Cl)R, and Cp₂Ti(Cl:AlH₂Cl)R (R=H and CH₃) were calculated by ab initio molecular orbital methods. These six reaction mechanisms were compared. Of the two possible reaction paths, attack of ethylene at Ti and the Cl and R ligands (path IN) and that from the opposite side of the Cl ligand (path OUT), the former is found to be more favorable, with a very low activation energy for reaction of ethylene with Cp₂Ti(Cl)H. For reaction of ethylene with Cp₂Ti(Cl)CH₃, the insertion transition states on both paths have almost the same energy barrier height above the reactants. For reaction of ethylene with Cp₂Ti(Cl:AlH₂Cl)R, the bond alternation between Ti–Cl and Cl–Al plays an important role in the mechanisms.