Effect of electric field on the nematic-isotropic phase transition of compounds with a strong longitudinal dipole moment

We present calculations on the effect of an external electric field on the nematic-iso-tropic transition of compounds with strong longitudinal dipole moments. In such compounds neighbouring molecules have antiparallel correlations. We use the Bethe cluster model and the constant coupling approximation in our calculations. Assuming reasonable values of the dipole moment and polarizabilities of the molecules, it is predicted that the nematic-(field induced) paranematic transition becomes continuous for an internal field E ≈ 3250 esu, when the transition point is ~ 6°K above the field-free value

Scaled particle theory of a system of right circular cylinders subjected to an attractive potential

We extend the scaled particle theory of a system of hard right circular cylinders by including a mean field attractive potential of the Maier and Saupe type. The order parameters, internal energy change, density change and the isothermal compressibility of the isotropic phase at the nematic-isotropic transition point are studied for various values of R the radius to height ratio of the cylinders. As in the case of the hard right circular cylinders, there is an approximate symmetry in the phase transition properties between the disc-like and rod-like regions when plotted as functions of the ratio of the larger to smaller dimension of the cylinders

The nematic-isotropic phase transition: application of the Andrews method

We have extended the Andrews method to derive the thermodynamic properties of an ensemble of spherocylinders. In the case of hard spherocylinders, by using the virial coefficients of the isotropic phase which agree with the results of recent computer simulation studies, we have determined several properties near the nematic-isotropic phase transition point in the mean field approximation. Including the attractive part of the potential, the values derived from the model are in reasonably good agreement with experimental data and in fact show considerable improvements over the currently available model calculations. In particular, the results are compared with those based on the scaled particle theory

MOS11: A New Component in the mRNA Export Pathway

Nucleocytoplasmic trafficking is emerging as an important aspect of plant immunity. The three related pathways affecting plant immunity include Nuclear Localization Signal (NLS)–mediated nuclear protein import, Nuclear Export Signal (NES)–dependent nuclear protein export, and mRNA export relying on MOS3, a nucleoporin belonging to the Nup107–160 complex. Here we report the characterization, identification, and detailed analysis of Arabidopsis modifier of snc1, 11 (mos11). Mutations in MOS11 can partially suppress the dwarfism and enhanced disease resistance phenotypes of snc1, which carries a gain-of-function mutation in a TIR-NB-LRR type Resistance gene. MOS11 encodes a conserved eukaryotic protein with homology to the human RNA binding protein CIP29. Further functional analysis shows that MOS11 localizes to the nucleus and that the mos11 mutants accumulate more poly(A) mRNAs in the nucleus, likely resulting from reduced mRNA export activity. Epistasis analysis between mos3-1 and mos11-1 revealed that MOS11 probably functions in the same mRNA export pathway as MOS3, in a partially overlapping fashion, before the mRNA molecules pass through the nuclear pores. Taken together, MOS11 is identified as a new protein contributing to the transfer of mature mRNA from the nucleus to the cytosol

Scaled particle theory of a system of spherocylinders: extension of calculations to high pressures

The viscosity coefficients of nematic substances for corresponding orientation geometry introduced and measured for PAA and PAP by the author in the thirties are discussed from the actual point of view. The great universality of these coefficients of viscosity and their utility for describing several dynamical phenomena has been shown. There is a quantitative agreement between the experimental data of those investigations and continuum hydrodynamical theory of nematics with the numerical values of viscosities measured by the author. As a new field of application of flow in definite orientation geometry, the properties of smectics and closely connected problems of phase transitions, pretransition effects and reentrant phase has been discussed

Equivalence of the Krieger-James approximation and the constant-coupling approximation in magnetism

We have applied the Krieger-James approximation to a description of short range order effects in both ferro- and antiferromagnetism. In this method, a mechanical consistency condition is imposed on the probability distribution of a pair of near neighbours in a cluster of (Z+1) ions. The resulting theory is analytically equivalent to the familiar constant coupling approximation, thus ensuring thermodynamic equilibrium of the system

Joy Mining Co. peat deposit field trip near Colville, WA.

Joy Mining Co. peat deposit field trip near Colville, WA.https://digitalmaine.com/mgs_geologic_field_photos/3372/thumbnail.jp

Extension of McMillan's model to liquid crystals of disc-like molecules

McMillan's mean field model of smectic A is extended so that the translational order parameter is now periodic in two dimensions. The theory is developed for a face-centered rectangular lattice composed of liquid-like columns, taking the molecular cores to be circular discs normal to the columnar axes but with an asymmetrical disposition of the chains. When the axial ratio b/a =square root 3, the rectangular lattice reduces to a hexagonal one and the theory becomes essentially identical to that. proposed very recently by Feldkamp , Handschy and Clark. When b/a = square root 3 or departs from it only slightly, it turns out that the transition from the columnar to the isotropic phase may take place either directly or via a nematic phase, depending on the model potential parameters (a). Interpreting a to be a measure of the chain lengths as in McMillanls theory, the phase diagram is in broad agreement with the trends exhibited by the hexa-n-alkoxybenzoates of triphenylene. For higher values of b/a the theory predicts a columnar-smectic A transition as well. The new smectic A phase is biaxial. The possibility of such a phase occurring in real systems is discussed briefly