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The ability to depress the resonance intensity of (23)Na in rat liver tissue was not found in the supernatant fraction. It was exclusively localized in particulate fractions. The intensity and saturation behavior of the (23)Na signal was examined in suspensions containing various amounts of the particulate fraction of rat liver homogenate. The results strongly suggest that the (23)Na signal of tissue reflects quadrupole interactions and does not result from a slow exchange between the free and bound fractions of Na(+). The activity coefficient of Na(+) in rat liver homogenate (no medium was added) was 0.59, about 20% less than that in the isotonic saline. Available evidences and discussion indicate that the bound Na(+) in the homogenate is much less than the so-called "NMR-invisible" fraction of Na(+).

The theoretical line-shape function of the nuclear magnetic resonance (NMR) signal of (23)Na in biological tissue (and other unoriented systems) was obtained under the following conditions: (I) there occur two states of (23)Na in the system, (II) the exchange of (23)Na between the two states is rapid (but not too rapid), (III) in the absence of exchange, the (23)Na in one state is characterized by a single transverse relaxation time T(2) and a single Larmor frequency, and (IV) in the absence of exchange, the (23)Na in the other state possesses (a) two different values of T(2) and/or (b) more than one Larmor frequencies in the first order perturbation effect. The theoretical signal obtained consists of two Lorentzian components, which are centered at the same frequency, but characterized by different T(2). Only the narrower component, comprising 40% of the total intensity, is visible, when the fast T(2) is sufficiently short. The theoretical line-shape function of (23)Na signal was also calculated for oriented systems in which the above conditions are fulfilled.

Speech sound errors exhibited by three conduction and three Broca's aphasic patients on naming and word-repetition tasks were subjected to phonemic and subphonemic analyses. In the conduction aphasic patients, errors occurred equally often on consonants and vowels in both the naming and word-repetition tasks, while in the Broca's aphasic patients errors occurred selectively on consonants. Transposition errors occurred almost as often as substitution errors in the conduction aphasic patients, while substitution errors constituted the majority of errors in the Broca's aphasic patients. The Broca's aphasic patients, as compared to the conduction aphasic patients, exhibited a markedly higher number of substitution errors occurring between phonemes separated by a single subphonemic feature on the naming task. On the basis of these findings, it was hypothesized that the differences in the error patterns of the two types of aphasia reflected differences in the underlying mechanisms of the impairment in each type.

An electrostatic calculation suggests that when an ion is bound near the mouth of a channel penetrating a low-dielectric membrane, a counter ion may form an ion pair with this ion. The tendency towards ion-pair formation is remarkably enhanced at channel mouths by forces (image forces) arising from the charges induced on the boundaries between different dielectrics. The binding constant for the formation of ion-pairs of monovalent ions is estimated under the assumption that local interactions between the counter ion and the channel wall are negligibly small. It is of the order of 1–10 molal−1 or more for the binding of a Cl− (F−) counter ion to an Na + ( Li + ) ion if appropriate conditions are fulfilled. The binding constant depends on the position of the binding site, the dimensions and geometries of the channel and channel mouth, and the state of ion loading of the channel, as well as the ionic species. The present results also indicate that when cation (anion) channels have anionic (cationic) groups as integrant parts of their channel walls, interactions between these charged groups and permeant ions are markedly enhanced by the image forces.

Les resultats de l'homopolymerisation et de la copolymerisation du styrene et de l'indene et des resultats anterieurs suggerent que la polymerisation syndiotactique du styrene s'effectue selon un mecanisme cationique avec coordination