Doppler-free two-photon excitation spectroscopy and the Zeeman effects. Perturbations in the 14(0)1 and 1(0)(1)14(0)1 bands of the S1 <-- S0 transition of C6D6

Doppler-free two-photon excitation spectra and the Zeeman effects for the 1 band of the S1 1B2u <-- S0 1A1g transition in gaseous benzene-d6 were measured. Although the spectral lines were strongly perturbed, almost all of the lines near the band origin could be assigned. From a deperturbation analysis, the perturbation near the band origin was identified as originating from an anharmonic resonance interaction. Perturbation centered at K = 28-29 in the 14(0)1 band was analyzed, and it was identified as originating from a perpendicular Coriolis interaction. The symmetry and the assignment of the perturbing state proposed by Schubert et al. (Schubert, U.; Riedle, E.; Neusser, H. J. J. Chem. Phys. 1989, 90, 5994.) were confirmed. No perturbation originating from an interaction with a triplet state was observed in both bands. From the Zeeman spectra and the analysis, it is demonstrated that rotationally resolved levels are not mixed with a triplet state. The intersystem mixing is not likely to occur at levels of low excess energy in the S1 state of an isolated benzene. Nonradiative decay of an isolated benzene in the low vibronic levels of the S1 state will occur through the internal mixing followed by the rotational and vibrational relaxation in the S0 state.     

Homopolymerizations and random copolymerizations of olefins with amino‐substituted cyclopentadienylchromium complexes

1‐(2‐N,N‐Dimethylaminoethyl)‐2,3,4,5‐tetramethylcyclopentadienyl‐chromium dichloride ( 1 ), (2‐N,N‐dimethylaminoethyl)cyclopentadienylchromium dichloride ( 6 ), and (2‐N,N‐dimethylaminoethyl)indenylchromium dichloride ( 7 ) in the presence of modified methylaluminoxane exhibit high catalytic activities for the polymerization of ethylene with random copolymerizations of ethylene with propylene, ethylene with 1‐hexene, and propylene with 1‐hexene. These initiators conduct polymerizations to give high molecular weight polymers with low polydispersities. However, the stereoregularities are very poor in these reactions. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2759–2771, 2002     

Structure and chemical behavior of an organoaluminum compound [Rb2AlOCR′NPh]2, a stereospecific catalyst for polymerization of acetaldehyde

A series of organoaluminum compounds [R₂AlOCR′NPh]₂, which are the reaction products between trialkylaluminum compounds and secondary acid amides and are excellent catalysts for stereospecific polymerizations of aldehydes, were isolated in the crystalline state. Chemical behavior of such compounds toward Lewis acids and bases were interpreted in terms of the structures of [Me₂AlOCPhNPh]₂ and its trimethylamine oxide complex Me₃NO·AlMe₂OCPhNPh which were determined by X-ray structure analyses. Reaction products of primary and tertiary acid amides with trialkylaluminum compounds were also studied.     

New Combinatorial Bounds for Authentication Codes and Key Predistribution Schemes

This paper provides new combinatorial bounds and characterizations of authentication codes (A-codes) and key predistribution schemes (KPS). We first prove a new lower bound on the number of keys in an A-code without secrecy, which can be thought of as a generalization of the classical Rao bound for orthogonal arrays. We also prove a new lower bound on the number of keys in a general A-code, which is based on the Petrenjuk, Ray-Chaudhuri and Wilson bound for t-designs. We also present new lower bounds on the size of keys and the amount of users' secret information in KPS, the latter of which is accomplished by showing that a certain A-code is hiding inside any KPS.     

Strong continuity implies uniform sequential continuity

Uniform sequential continuity, a property classically equivalent to sequential continuity on compact sets, is shown, constructively, to be a consequence of strong continuity on a metric space. It is then shown that in the case of a separable metric space, uniform sequential continuity implies strong continuity if and only if one adopts a certain boundedness principle that, although valid in the classical, recursive and intuitionistic setting, is independent of Heyting arithmetic.     

Dual-gradient capillary electrochromatography by varying the mobile phase composition and applied voltage.

Dual-gradient capillary electrochromatography (DG-CEC) was developed to provide superior performance with regard to the separation of ionized analytes; in this method, both the eluent composition and the applied voltage are varied during the separation procedure. As for the gradient in the eluent composition, a shift in the pH is employed to control not only the electrophoretic mobility, but also the retention factor of the analytes. The dual-gradient method was shown to be effective in increasing the resolution and reducing the chromatographic period of ionized analytes. Fourteen kinds of o-phthalaldehyde labeled amino acids were separated within 8 min using DG-CEC with multistage enlargement in the applied voltage. The separation efficiency increased particularly for highly retained amino acids in the dual-gradient, as compared to those in the ordinary single-gradient for the eluent.     

A bioelectrocatalysis method for the kinetic measurement of thermal inactivation of a redox enzyme, bilirubin oxidase.

The thermal stability of a redox enzyme, bilirubin oxidase (BOD), has been quantitatively evaluated by measuring the inactivation kinetics of BOD at several temperatures. The enzyme activity is directly related to the mediated bioelectrocatalytic current for the BOD-catalyzed reduction of O(2). Thus, the inactivation process is measured by the time-dependent decrease in the bioelectrocatalytic current. The results reveal that the inactivation obeys first-order kinetics, whose rate constants (k) are determined at pH 7.0 and at 50 - 70 degrees C. The half life of BOD activity, calculated from the k value at 50 degrees C is 114 min, which is in harmony with the thermal-stability data given in a catalog by Amano Enzyme Inc. The bioelectrocatalysis method allows in situ measurements of the inactivation kinetics in the period of a few minutes at relatively high temperatures. The rate constants show a large temperature dependence, leading to a large Arrhenius activation energy (E(A)) of 221 kJ mol(-1). The activation Gibbs energy (DeltaG(not equal)), activation enthalpy (DeltaH(not equal)), and activation entropy (DeltaS(not equal)) are also determined.     

Identification of ammonia in gas emanated from human skin and its correlation with that in blood.

Identifying and measuring the ammonia gas that emanates from human skin, which we called skin gas, has been achieved using a modified gas chromatographic system with a nitrogen-selective detector (flame-thermoionic detector: FTD). The skin gas is collected with a home-made sampling probe or bag, which is used to cover the skin surface of a subject's wrist, or a finger, for 5 min. It was proved that ammonia was present in skin gas for healthy persons and patients with hepatic disease. The average amounts of ammonia were 1.7 +/- 0.4 and 2.7 +/- 0.8 ng/cm2; furthermore, there was a significant difference between them (p < 0.05). In addition, the ammonia levels present in skin gas were correlated with that in blood (r = 0.64, p < 0.05).     

Zirconia-based amperometric sensor using La–Sr-based perovskite-type oxide sensing electrode for detection of NO2

An amperometric zirconia-based sensor attached with perovskite-type oxide sensing electrode was examined for monitoring NO₂ in automobile exhaust. The sensor using La_0.6Sr_0.4Co_0.98Mn_0.02O₃ showed high response to NO₂. The response was almost linear to NO₂ concentration in the range between 50 and 800 ppm, and a 90% reaction time to 400 ppm NO₂ was less than 20 s. Though the NO₂ response of the sensor was slightly affected by the changes in O₂ concentrations, it showed still high response in the examined range of 5–21 vol%.