Atrial activity during thePR segment of the MCG

Summary Sloping signals were observed in thePR segment of normal magnetocardiograms recorded from five dogs. Larger ramps were observed after first-degree AV nodal blockade was induced pharmacologically, and complete atrial repolarization was observed following isolated atrial contractions in two animals with second-degree block. These ramps, ranging up to 6.7 pT in size and arising from the atria, may complicate magnetic detection of His-Purkinje activity. This work was supported by the National Institute of Health under Grant No. HL 23184.     

Anchoring strength coefficient of a monomer and its dimer at a polymer-coated interface

The dialkoxyphenylbenzoate monomer '5005' (C₅H₁₁OC₆H₄COOC₆H₄OC₅H₁₁) and its dimer were aligned parallel to a buffed polyimide-coated glass substrate. A magnetically induced Freedericksz transition in both thick and thin cells was used in conjunction with a capacitance technique to determine the anchoring strength coefficient Was a function of temperature in the nematic phase. It was found that for both monomer and dimer, Wincreases with decreasing temperature. The anchoring coefficient for the dimer, however, was found to be an order of magnitude larger than for the monomer at comparable reduced temperatures. The splay elastic moduli were also determined for both species, and found to be of comparable magnitude, consistent with previous results.     

Thermal Properties of Binary Mixtures of Liquid Crystals. A Review

Owing to their wide range of industrial utility, binary systems of liquid crystals are currently a topic of extensive studies. This paper is a comprehensive review of the literature from 1973, where the review of Hsu et al. ⁹⁵ ended, through mid-1981. For simplification, the organization used here is similar to that incorporated in the previous review.

Because of the volumes of literature on mesophase systems, this study includes only binary mesophase systems in which both components are thermotropic mesogens. Included here are only those systems for which phase diagrams have been constructed or systems which are similar to those whose phase diagrams have been constructed.

Much of the work on binary mixtures is done by industrial applications specialists and thus was not available for this review. Inevitably, there will be omissions from published work, although every attempt was made to include all of the available literature.