Neutral carrier-based Na+-selective electrode for application in blood serum

The ionophore N,N,N,N-tetracyclohexyl-1,2-phenylenedioxydiacetamide (4) shows higher lipophilicity and superior Na⁺/K⁺ selectivity than the previously described N,N-dibenzyl-N,N-diphenyl-1,2-phenylenedioxydiacetamide (2). It is a suitable component of Na⁺-selective liquid membrane electrodes for the assay of Na⁺ in clinical analysers.On leave from Hitachi Ltd., Central Research Laboratory, Kokubunji, Tokyo 185, Japan.     

Determination of 2',3'-dideoxyinosine and 2',3'-dideoxyadenosine in rat plasma by high-performance liquid chromatography with precolumn fluorescence derivatization.

A high-performance liquid chromatographic method with precolumn fluorescence derivatization using 2-(5-chlorocarbonyl-2-oxazolyl)-5,6-methylenedioxybenzofu ran is described for the quantification of 2',3'-dideoxyinosine, a therapeutic drug for acquired immunodeficiency syndrome, and 2',3'-dideoxyadenosine, an anti-human-immunodeficiency-viral agent, in rat plasma. The dideoxyribonucleosides and 3'-deoxythymidine (internal standard) in rat plasma (0.1 ml) are cleaned up by a solid-phase extraction technique using an octadecyl silica (ODS) cartridge, Toyopak ODS M, and the dideoxyribonucleosides in the eluate are reacted with the reagent to produce the corresponding fluorescent esters. The esters are separated by chromatography on a reversed phase column, TSKgel ODS-80TM. The detection limits (signal-to-noise ratio = 3) for the dideoxyribonucleosides are 1.3-5.4 pmol on column. Plasma concentrations of 2',3'-dideoxyinosine after intra-jugular-venous administration to rat can be monitored by this method.     

A chemiluminogenic substrate for N-acetyl-beta-D-glucosaminidase, o-aminophthalylhydrazido-N-acetyl-beta-D-glucosaminide

A new type of chemiluminogenic substrate for N-acetyl-beta-D-glucosaminidase, o-aminophthalylhydrazido-N-acetyl-beta-D-glucosaminide, was prepared by incorporating an enzyme-removable substituent, N-acetyl-D-glucosaminide group, into the hydrazide moiety of luminol. This substrate releases luminol upon enzymatic hydrolysis. The enzyme was detected chemiluminescently using this substrate.     

Drawing of ultrahigh-molecular-weight polyethylene single-crystal mats: The crystallinity

Single-crystal mats of ultrahigh-molecular-weight polyethylene can be drawn uniformly to high draw ratios, more than 20χ at the highest, after the necking process is completed. The dynamic mechanical modulus of the drawn mats increases markedly during the uniform drawing stage. The structural changes induced by the uniform drawing at 100°C have been followed by wide-angle and small-angle x-ray scattering, infrared absorption, differential scanning calorimetry, and birefringence. The crystallinity is estimated from the x-ray amorphous scattering intensity, the IR absorbance of gauche bands, the heat of fusion from DSC, and the density. The estimated crystallinities of the drawn mats are all very high and increase slightly and monotonically with increased drawing after necking, though the values of the crystallinity depend on the method of estimation. IR gauche bands and the SAXS peak due to the long period disappear at a draw ratio of about 80χ. All the results suggest that the uniform drawing after necking destroys the two-phase structure made up of alternately stacked crystalline and amorphous regions and then reorganizes it into a single-phase crystalline structure.     

Vibronic model of the stress effects on the relaxed excited state of the F center

A vibronic model of the stress effects on the relaxed excited state of the F center is studied by taking into account the Γ⁺₁, Γ⁺₃, and Γ^-₄-mode phonons. The vibronic parameters and stress coupling coefficients are determined for KCl. The orbital reduction is discussed.     

Experimental Discussion on Eye-Safe 1.54 μm Photon Counting Lidar Using Avalanche Photodiode

A Mie hdar system with an eye-safe wavelength of 1.54 m was developed and its performance characteristics were experimentally discussed. The wavelength was generated by a Nd:YAG based methane-shifted Raman laser. The collected backscattering light was detected by an InGaAs avalanche photodiode working in photon counting mode at that wavelength. Results of atmospheric observation showed clearly the dynamics of multi-layered cluds up to an altitude of 7 km. The systems performance was confirmed on the point of signal to noise ratio in both the observation and the simulation. Advantages of the eye-safe 1.54 m wavelength in lidar atmospheric research and system limitations were discussed. © 2004 The Optical Society of Japan     

A dodecameric porphyrin wheel

A dodecameric porphyrin wheel was prepared by Ag(I)-promoted intramolecular coupling of a linear porphyrin dodecamer and was observed by scanning tunneling microscopy (STM). Efficient energy hopping along the array was revealed by femtosecond transient anisotropy measurements.