Dressed atoms in flight through a periodic crystal field: X-VUV double resonance

We report the Autler-Townes doublet demonstrating a novel type of coherent interaction of atoms not with photons but with a periodic crystal field when the atom is in flight through a crystal at high velocity. It was observed by the nonoptical X-VUV (vacuum-ultraviolet) double resonance of three-dimensional resonant coherent excitation with good coherence. The states strongly coupled in the VUV region were probed by the excitation in the x-ray region. The characteristic spectra are well interpreted by an analogy of the dressed atom concept often adopted for the atom-photon interaction.     

Fluorescent solution microcapsules as ideal tracer particles in long-term tracking of 3-D Lagrangian trajectories

 Fluorescent solution microcapsules (diameter <100 μm) have been invented as tracer particles suitable for the long-term tracking of 3-D Lagrangian trajectories in the rotating annulus fluid experiments. In more than 10% of the tracking experiments, the microcapsule was observed to follow the flow passively for more than 10 h, at their maximum 18 h. Received: 21 May 1997/Accepted: 7 January 1998     

High-resolution solid-state 13C NMR study of ethylcellulose films

Ethylcellulose films cast from concentrated solutions of chloroform, benzene, and carbon tetrachloride were subjected to the NMR relaxation measurements including ¹H spin-lattice relaxation time (T_1H), rotating-frame ¹H spin-lattice relaxation time (T_1ρH), and ¹³C spin-lattice relaxation time (T_1C). The values of T_1ρH for carbons in the glucose units of ethyl-cellulose were of the same order of magnitude as those reported for the crystalline and noncrystalline regions of ramie cellulose. The values of T_1C for unsubstituted C2, C3 carbons were smaller than those for the corresponding carbons in the noncrystalline region of native celluloses. The T_1C values for unsubstituted C2, C3, and substituted C6 carbons showed a small but definite dependence on the solvent from which the films were cast. © 1993 John Wiley & Sons, Inc.     

Probing the behaviour of surface-adsorbed free radicals using ALC μSR

Preliminary investigations show that the avoided level crossing muon spin rotation technique is well suited to the study of surface-adsorbed free radicals. The samples used were monolayer films of benzene and anisole on small (7 nm and 14 nm) amorphous silica grains. The observed cyclohexadienyl radical resonances indicate a reduction in mobility down to a temperature of about 125 K, beyond which measurements are unreliable due to weak signals. However, the failure to observe any anisotropy in the resonances shows that the residual mobility is mainly translational. For a benzene multilayer, on the other hand, we found clear evidence of anisotropic behaviour, co-existing with signals from a mobile phase. It seems likely that this arises from a thin fluid surface layer in equilibrium with frozen bulk.     

Relationship between the transference of a drug from a transdermal patch and the physicochemical properties.

The transferred percentages of 13 drugs to rat skin from transdermal patches were studied to reveal the relationship to their physicochemical properties. The drugs to be tested had melting points of 13.5-234 degrees C, lipophilic indices of 0.475-5.336, and molecular weights of 122.12-392.45. The transferred percentage of drug to intact skin was lower, the higher the melting point, lipophilic index and molecular weight. The same was true in stripped skin, where the transferred percentage of drug was markedly increased. The difference between transferred drug percentages to stripped and intact skin, which could be regarded as the regulatory contribution of the stratum corneum, tended to be larger, the lower the drug's melting point and lipophilic index.     

NMR study of model compounds of vinyl polymers

Complicated NMR spectra of vinyl polymers provide conformational and configurational knowledge of the polymers in solution. Explicit expressions for the spectral frequencies and intensities are obtained by the analysis of vinyl polymers and their model compounds as weakly coupled systems. The classified spectra expected for common vinyl polymers are presented by using the results of the analysis. The analysis is applied to model compounds of poly(vinyl alcohol) and poly(vinyl acetate) in solution. The results show that conformations of poly(vinyl alcohol) are determined by the intramolecular hydrogen bonding so that the syndiotactic isomer forms a helical structure, the isotactic one a planar zigzag structure. The poly(vinyl acetate) produces a helical structure for isotactic isomer by the repulsion of side chains and a planar zigzag for the syndiotactic isomer.     

Silica with Bimodal Pores for Solid Catalysts Prepared from Water Glass

The comparison of bimodal pore structures between silica gels prepared from silicon alkoxide and from water glass was performed based on the results of phase separation tendency, mesopore formation, and atomic scale observation using ²⁹Si NMR. Macropore structure could be controlled for both the raw material systems by inducing phase separation. Although the gelation in the water glass system is much faster than that in the silicon alkoxide system, there is little difference in the atomic scale structure, mesopore evolution during processing, and phase separation tendency. The results suggest that the obtained bimodal porous silica from water glass is essentially the same as that from silicon alkoxide. Because of the low cost of water glass, water-glass-derived bimodal porous silica is applicable to industrial use.