Composite optical waveguide composed of a tapered film of bromothymol blue evaporated onto a potassium ion-exchanged waveguide and its application as a guided wave absorption-based ammonia-gas sensor.

For what is the first time to our knowledge, we have successfully evaporated a tapered film of bromothymol blue (BTB) onto a potassium ion-exchanged (PIE) waveguide to form a composite optical waveguide (COWG) for trace-ammonia detection. The BTB film has a high refractive index (1.69) and a smooth surface and is transparent to a 633-nm laser beam in air. In the COWG structure, the BTB film serves as a single-mode waveguide, and adiabatic transition of the TE(0) mode was realized between the BTB waveguide and the PIE waveguide with both BTB tapers. In the presence of ammonia, the BTB film changes color from yellow to blue, which causes absorption of the 633-nm guided wave. Our experimental results demonstrate that such a guided wave absorption-based ammonia-gas sensor is much more sensitive than one based on evanescent-wave absorption. A detection limit of part in 10(9) of ammonia has been realized for a BTB film-PIE glass COWG.

Characterization and application of a channel- planar composite waveguide.

A new structural waveguide, which is referred to as a channel-planar composite optical waveguide (COWG), has been fabricated by sputtering of a titanium dioxide (TiO>(2)) film onto a glass substrate with potassium ion-exchanged channel waveguides. By use of a mask during deposition, the TiO(2) film was formed into a 27-nm-thick, 5-mm-wide strip with two 1-mm-long tapered ends perpendicular to the channel waveguides. Adiabatic transition of the TE(00) mode and the TE(00)- TM(00) mode separation inside such a channel-planar COWG were demonstrated by combination of theoretical analysis and measurement of the experimental attenuation that arises from scattering loss and evanescent-field dye absorption. Changing the superstrate index in the region of the TiO(2) film in the channel-planar COWG yielded polarimetric interference patterns. This new technique can be applied to integrated optical chemical and biological sensors to produce enhanced sensitivity.

Measurement of the modal birefringence of single-mode K(+) ion-exchanged planar waveguides with polarimetric interferometry.

The polarimetric interference pattern on the surface of single-mode planar waveguides made by potassium ion exchange in soda-lime glass substrates can be observed through a 45 degrees analyzer, which allows for the high-precision measurement of the modal birefringence of samples in a wide range of 0 to 5 x 10(-4). Using this method, believed to be new, we investigated the effects of exchange temperature and time on the modal birefringence of single-mode potassium ion-exchanged waveguides. The modal birefringence profile was achieved by measurement of the variation of the phase difference between the TE(0) and the TM(0) modes with hydrofluoric-acid-etching depth of the sample.

Axially chiral N-benzyl-N,7-dimethyl-5-phenyl-1, 7-naphthyridine-6-carboxamide derivatives as tachykinin NK1 receptor antagonists: determination of the absolute stereochemical requirements.

A potent and orally active NK1 antagonist, trans-N-[3, 5-bis(trifluoromethyl)benzyl]-7,8-dihydro-N, 7-dimethyl-5-(4-methylphenyl)-8-oxo-1,7-naphthyridine-6-carboxamide (1t), was shown to exist as a mixture of separable and stable (R)- and (S)-atropisomers (1t-A and 1t-B) originating from the restricted rotation around the -C(6)-C(=O)- bond; the antagonistic activities of 1t-A were ca. 6-13-fold higher than those of 1t-B. Analogues of 1t (3), which have (S)- and (R)-methyl groups at the benzylic methylene portion of 1t, were prepared and separated into the diastereomeric atropisomers, 3a-A, 3a-B and 3b-A, 3b-B, in enantiomerically pure forms. Among the four isomers of 3, the (aR, S)-enantiomer (3a-A) exhibited the most potent antagonistic activities with an IC50 value of 0.80 nM (in vitro inhibition of [125I]BH-SP binding in human IM-9 cells) and ED50 values of 9.3 micrograms/kg (iv) and 67.7 micrograms/kg (po) (in vivo inhibition of capsaicin-induced plasma extravasation in guinea pig trachea), while the activity of the (aS,R)-enantiomer (3b-B) was the weakest with an IC50 value of 620 nM. The structure-activity relationships in this series of antagonists indicate that the (R)-configuration at the axial bond and the stacking (or stacking-like) conformation between the two phenyl rings as shown in 1t-A and 3a-A are essential for high-affinity binding and suggest that the amide moiety functions as a hydrogen bond acceptor in the interaction with the receptor.

The combination of photocatalysis and ozonolysis as a new approach for cleaning 2,4-dichlorophenoxyaceticacid polluted water.

Treatment of 2,4-D polluted waters with photocatalysis leads to the buildup of high concentrations of the long living intermediate 2,4-DCP. A new approach using a combination of ozonolysis and photocatalysis gave better degradation results with lower intermediate concentrations. The advantages of photocatalysis giving a constant decline in TOC and of ozonolysis giving no buildup of high intermediate concentrations were combined. Degradation data of 2,4-D for photocatalysis, ozonolysis and the combination of both for different pH ranges are given. Data on the main intermediate 2,4-DCP are given for the three different approaches.

[A case of Aicardi syndrome: neurophysiological investigation].

A Japanese girl developed tonic spasms in series at two months after birth. When she was admitted at 4 months, she had generalized muscle hypotonia and could not control her head. She had atotal agenesis of the corpus callosum on MRI, reticulo-lacunitis revealed by ophthalmologic examination, and hypsarrhythmia in EEG. Brain stem auditory evoked potentials and flash-visual evoked potentials exhibited abnormally asymmetrical findings. The cortical components of somatosensory evoked potentials were not elicited on admission, but some components became to be recognized on median nerve stimulation in accordance with improvement of EEG findings after various therapeutic trials. We concluded that these neurophysiological examinations were useful to investigate the abnormal lesions of the central nervous system in patients with Aicardi syndrome.