Facile Multiple Alkylations of C60 Fullerene

The reduction of fullerene (C₆₀) with sodium dispersion in the presence of an excess amount of dipropyl sulfate was found to yield highly propylated fullerene, C₆₀(nC₃H₇)_n (max. n = 24), and C₆₀(nC₃H₇)₂₀ was predominantly generated as determined by mass spectroscopy.     

Effects of 2-hydroxypropyl α-cyclodextrin on the radioactive iodine sorption on activated carbon

Journal of Radioanalytical and Nuclear Chemistry - Effect of 2-hydroxypropyl α-cyclodextrin (α-HPCD) on the iodine adsorption onto activated carbon (AC) was investigated. The iodine...     

A convenient synthesis of olefins via deacylation reaction

A convenient and environmentally-friendly synthetic method of olefins via deacylation reaction is described. The reaction gives olefins by condensation of aldehydes with a variety of 1,3-dicarbonyl compounds in the presence of anhydrous potassium carbonate at room temperature in high yields (70-90%) in one step. The synthetic potential of this strategy can be used as an alternative procedure to the Wittig, Wittig-Horner reactions. The stereochemistry of the resulted olefins was determined by NOE experiment with correct radio frequency and X-ray analysis. The E/Z selectivity of the deacylation reaction depends on the α-substituents of the 1,3-dicarbonyl compounds.     

Alterations of plasma and cerebrospinal fluid glutamate levels in rats treated with the N-methyl-D-aspartate receptor antagonist, ketamine

It has been reported that the repeated administration of a sub-anesthetic dose of an N-methyl-D-aspartate receptor antagonist, ketamine, can produce an animal model of schizophrenia. Since no information is available on the alterations of the amino acid levels in ketamine-treated rats, we investigated the amino acid composition in the plasma and cerebrospinal fluid of rats that were repeatedly administered with ketamine for 5 consecutive days (30 mg/kg/day). The plasma and cerebrospinal fluid amino acid compositions in the fifth week after cessation of repeated ketamine administration were determined by highperformance liquid chromatography with fluorescence detection using a pre-column fluorescence reagent, i.e. 4-fluoro-7nitro-2,1,3-benzoxadiazole. Among the amino acids investigated in the present study, the level of plasma glutamic acid increased significantly (p < 0.05), while that of the cerebrospinal fluid glutamic acid decreased significantly in the ketamine-treated rats as compared with these levels in control rats injected with saline (p < 0.05, n = 7). These alterations in the glutamic acid level in the plasma and cerebrospinal fluid resemble those in schizophrenic patients, suggesting that ketamine-treated rats may be a useful model for performing research on the pathophysiology of schizophrenia.     

Parallel two-step phase-shifting digital holography using polarization

We propose an optical implementation of a parallel two-step phase-shifting digital holography that utilizes a polarization technique. The implementation uses a phase-shifting array device consisting of a retarder array attached to an image sensor, and does not require the optical system to image the phase-shifting array device onto the image sensor required for the previously reported optical implementation of the parallel two-step phase-shifting digital holography. Then, the proposed implementation is essentially simple to align and compose. A preliminary experiment showed that the parallel two-step phase-shifting digital holography based on the proposed implementation can remove the conjugate image clinging to the image reconstructed by Fresnel transform alone with DC term suppression. Also, when the reconstruction distance was changed, the qualities of the reconstructed images were quantitatively evaluated by using normalized root-mean-square error. It was clarified that the proposed implementation was superior to other parallel phase-shifting digital holographies and Fresnel transform alone. Thus, the validity of the proposed implementation was confirmed.     

Preparation and improvement in photovoltaic performance of dye-sensitized solar cells using carbon dioxide

We report preparation and improvement in photovoltaic performance of N719-based dye-sensitized solar cells (DSSCs) using pressurized carbon dioxide (CO₂) as a co-solvent for the absorption process on the TiO₂ photoelectrode surface. Effective absorption of the N719 molecules on the TiO₂ surface was achieved using CO₂ processing, and the absorption time was shortened drastically from 24 h (in the dip process) to less than 3 h. The cells prepared under pressurized CO₂ for the absorption showed greater photovoltaic performance, especially higher short-circuit current density and conversion efficiency, compared with that from typical dip method. It was revealed that the suitable CO₂ pressure for the absorption was 5 MPa and the efficiency was achieved to be more than 7.5 %. Prevention of back electron transfer reactions from TiO₂ to oxidized dyes or iodides was caused currently, because the homogeneous coverage of N719 molecules on the TiO₂ surface was obtained by the use of pressurized CO₂.     

Catalytic Reduction of Dinitrogen into Ammonia and Hydrazine by Using Chromium Complexes Bearing PCP-Type Pincer Ligands**

A series of chromium-halide, -nitride, and -dinitrogen complexes bearing carbene- and phosphine-based PCP-type pincer ligands has been newly prepared, and some of them are found to work as effective catalysts to reduce dinitrogen under atmospheric pressure, whereby up to 11.60 equiv. of ammonia and 2.52 equiv. of hydrazine (16.6 equiv. of fixed N atom) are produced based on the chromium atom. To the best of our knowledge, this is the first successful example of chromium-catalyzed conversion of dinitrogen to ammonia and hydrazine under mild reaction conditions.     

Photoredox- and Nickel-Catalyzed Hydroalkylation of Alkynes with 4-Alkyl-1,4-dihydropyridines: Ligand-Controlled Regioselectivity

Dual photoredox- and nickel-catalyzed hydroalkylation of terminal alkynes with 4-alkyl-1,4-dihydropyridines under visible light irradiation to afford Markovnikov- or anti-Markovnikov-type alkylated alkenes in good-to-high yields has been achieved, in which the regioselectivity of the products was effectively controlled by coordination ligands for nickel species. Using [NiCl₂(dtbbpy)] as a catalyst led to the formation of Markovnikov-type products, whereas using NiCl₂ ⋅ 6 H₂O led to the formation of anti-Markovnikov-type products.     

Atom-probe field-ion microscopy of GaAs and GaP

The atom-probe field-ion microscope (atom-probe FIM) was applied for the first time to GaAs and GaP which belong to the III–V compound semiconductors. The general character of the pulsed field-evaporation of GaAs and GaP was quite similar. Ga field-evaporated predominantly in the form of singly charged ions. As and P also field-evaporated mainly as singly charged ions, but their abundances were small compared with Ga⁺. It appears that As (or P) atoms can field-evaporate more easily in the form of AsO⁺ (or PO⁺) in the presence of oxygen on the surface. In all experiments, GaAsⁿ⁺ and GaPⁿ⁺ were rarely detected. After chemical etching the surfaces were covered with oxide films and various oxide ions were detected. The abundance of oxide ions dramatically decreased after field evaporation in hydrogen. No distinct difference between the 〈111〉 orientations of these materials which have zinc-blende structure could be observed. Most of the experimental results obtained were explained in terms of the existing theory of field evaporation. It was concluded that field penetration effects have a considerable influence on the field evaporation processes of these materials as well as on the field ionization processes.     

Molecular Flow and Lanthanum -Catalyzed Bond Interchange in Sodium Phosphate Polymers

Abstract

It is observed that sodium phosphate polymers, in which some of the Na⁺ ions have been replaced by La³⁺ ions, are subject to both simple molecular flow and to bond interchange in the glass transition region. These two relaxation mechanisms are separated, and their relative contributions to the shear viscosity are calculated. It is shown that the bond-interchange mechanism is subject to an activation energy of ca. 50 kcal, while that of the molecular flow is of the order of 200 kcal at Tg + 30°C;the latter is of the WLF form. It is further shown that the La³⁺ ions act as cross-links, at least at low concentrations, and that bond interchange occurs at the site of the La³⁺ ions rather than at random along the polymer chain.