Quasi-solid-state dye-sensitized solar cells using room temperature molten salts and a low molecular weight gelator

A dye-sensitized solar cell fabricated using the room temperature molten salt, 1-hexyl-3-methylimidazolium iodide, iodine and a low molecular weight gelator as a quasisolid-state electrolyte showed a 5.0% light-to-electricity conversion efficiency under AM 1.5 irradiation, and high-temperature stability.     

Discontinuous pressure effect upon enantiodifferentiating photosensitized isomerization of cyclooctene

A hydrostatic pressure of up to 750 MPa induced discontinuous changes in the enantiomeric excess of the (E)-isomer obtained in the enantio-differentiating photoisomerization of (Z)-cyclooctene and (Z,Z)-cycloocta-1,5-diene, sensitized by chiral benzene-1,2,4,5-tetracarboxylates; indicating a switching of the enantio-differentiation mechanism, which is attributable to dramatic conformational changes of chiral alkoxycarbonyl auxiliaries at a specific pressure.     

Achievement of a 920-MHz high resolution NMR

We have developed a 920-MHz NMR system and performed the proton NMR measurement of H(2)O and ethylbenzene using the superconducting magnet operating at 21.6 T (920 MHz for proton), which is the highest field produced by a superconducting NMR magnet in the persistent mode. From the NMR measurements, it is verified that both homogeneity and stability of the magnet have a specification sufficient for a high resolution NMR.     

A highly stereoselective synthesis of 11Z-retinal using tricarbonyliron complex

A stereoselective synthesis of 11Z-retinal 2, which is the chromophore of visual pigment (rhodopsin), was accomplished from the beta-ionylideneacetaldehyde-tricarbonyliron complex 3. The Peterson reaction of 3 using ethyl trimethylsilylacetate smoothly proceeded to afford predominantly the Z-ester 6. Transformation of the Z-ester 6 to the methyl ketone 19, followed by the Emmons-Horner reaction of 19 with C2-cyanophosphonate, produced ethyl 11Z, 13E-retinonitrile-tricarbonyliron complex 21 as the only product. Decomplexation of 21 with CuCl2 and subsequent DIBAL reduction gave 11Z-retinal 2 in excellent yield. Mechanistic consideration of Z-selectivity in the Peterson reaction of the aldehyde-tricarbonyliron complex is also discussed.     

Difference-frequency terahertz-wave generation from 4-dimethylamino-N-methyl-4-stilbazolium-tosylate by use of an electronically tuned Ti:sapphire laser

Among nonlinear materials, the organic ionic salt crystal 4-dimethylamino- N -methyl-4-stilbazolium-tosylate (DAST) is known for its large nonlinearity. We generated a coherent terahertz (THz) wave, using DAST, from the difference frequency between two oscillating wavelengths of an electronically tuned Ti:sapphire laser. In LiNbO(3), LiTaO(3), KTiOPO(4), and GaP crystals, THz-wave generation was not observed under the same experimental conditions. This result proves the high efficiency of DAST crystals for generation of difference-frequency THz waves.     

Low-frequency and high-frequency relaxations in dynamic electric birefringence of poly(γ-benzyl-L-glutamate) in m-cresol

The dc component Δn of the electric birefringence of poly(γ-benzyl-L -glutamate) in m-cresol is measured under an ac electric field at frequencies from 0.5 Hz to 200 kHz for solutions covering the dilute and semidilute regions. The dispersion curve indicates that at low frequencies Δn decreases with increasing frequency (low-frequency relaxation). For high-molecular-weight polymers at high concentration, Δn becomes negative at high frequency and its absolute value decreases with further increase in frequency (high-frequency relaxation). A unified theory for the two relaxations is developed on the basis of a model in which, in the semidilute regime, the rodlike polymer is confined in a cage formed by neighboring polymers and the lifetime of the cage lies between relaxation times of the two relaxations. The low-frequency relaxation is ascribed to end-over-end rotation of the polymer and the high-frequency relaxation to the rotation within a limited angle in the cage. The dependences of relaxation parameters on polymer concentration and molecular weight are reasonably explained by the theory.     

Dispersion relation approach to the anomalous magnetic moment in gauge theories

The reason why the dispersion relations for the anomalous magnetic moment are not valid in gauge theories is explained. New sum rules are derived based on unitary bounds of scattering amplitudes. In gauge theories these sum rules give the correct values for the anomalous magnetic moment, while, in the case of conventional renormalizable theories which contain no massive vector bosons, they are identical with the usual dispersion relations for the anomalous magnetic moment.     

Neutralization of static electricity charged on running vinyl chloride sheet by the use of soft beta-ray sources (author's transl)

The feasibility of 147Pm and 3H beta-ray sources as static eliminator was experimentally investigated. A sheet of vinyl chloride of 0.1 mm in thickness was used as an example of electrified materials. Its surface charge densities before and after beta-ray neutralization were measured as the function of electrostatic charge changing the speed of the sheet and the distance between the beta-ray source and the sheet. With a 147Pm beta-ray source of 200mCi in effective activity, almost complete neutralization was found for the sheet with the charge density less than 6 X 10(-6) C/m2 running at the speed of 0.18 m/s. In the case of the running speed of 0.5 m/s frequently used in industry, the electrostatic charge below 3 X 10(6) C/m2, where corona discharger is not so effective, was also perfectly eliminated. It was found that the optimal distance between the beta-ray source and the sheet was 10 cm in the case of 147Pm. The use of 3H beta-ray source of 1 Ci was not satisfactory. These results demonstrate that 147 Pm beta-ray source operates most efficiently as static eliminator when the charge density of material and/or its moving speed is not high.     

Synthesis of DTPA-conjugated (1,4)-linked 2-aminoglycosides varying in the anomeric configuration and their MRI contrast effect

We describe the efficient synthesis of DTPA-conjugated oligosaccharides composed of alpha- and/or beta-linked tri to monoglucosamines. Gd(iii) complex with DTPA-conjugated chitotriitol has been reported to be an effective MRI contrast agent. In order to elucidate the structure-property relationships, we planned to synthesize the DTPA-conjugated 2-amino-tri-, di-, and monosaccharides varying in configuration at the anomeric positions and the C2 position on the reducing end. Our strategy for the synthesis of the DTPA-conjugated oligosaccharides involves O-perbenzyl protected 2-amino-tri-, di-, and monosaccharides as key intermediates. The 2-aminoglycosides were prepared by non-selective glycosidation of 2-azido-2-deoxyglycosyl donors, followed by separation of two anomeric isomers. Although the synthesis involves separation of the stereoisomers, it circumvents not only the careful tuning of reaction conditions, but also the time-consuming preparation of glycosyl donors attached to different protecting groups. The protected 2-aminoglycosides were converted to the fully deprotected DTPA-conjugated tri- to monosaccharides by the same operation. MRI phantom study using the Gd(III) complexes of DTPA-conjugated oligosaccharides indicates that the number of the monosaccharide units was critical for enhancing the relative signal intensity of water protons per Gd, and various stereoisomers would be candidate scaffolds for MRI contrast agents.