First-order Fréedericksz transition above the nematic-smectic-a phase transition

The Fréedericksz transition is investigated for thin homeotropic cells of a negative dielectric anisotropy liquid crystal above its nematic-smectic-A phase transition temperature in a spatially uniform electric field. For very thin cells, a crossover from second- to first-order Fréedericksz behavior is observed; no additional fields are necessary. The results are consistent with the theory of Shi [Liq. Cryst. 29, 121 (2002)]].     

Possible structures for the lamellar-isotropic (Lam-I) and lamellar-nematic (Lam-N) liquid crystalline phases

The three refractive indices of a liquid crystal that exhibits lamellar analogues of the three-dimensional isotropic, nematic, and smectic A phases are reported as functions of temperature for the Lam-I and Lam-N phases. The data suggest a number of striking behaviour types. The orientational distribution of the mesogenic moieties becomes more highly peaked in two dimensions on cooling from the Lam-I to the Lam-N phase; the two-dimensional order associated with mesogenic director n in the Lam-N phase is weak; and conformational changes in the side chain result in an increase in the refractive index perpendicular to the lamellae with decreasing temperature in the Lam-N phase.     

MA(σ-centered): Cohen reals,strong measure zero sets and strongly meager sets

We prove thatMA(σ-centered) + the Dual Borel Conjecture is consistent; and thatMA(σ-centered) + the non-additivity of the ideal of the strong measure zero sets also is consistent. Jaime Ihoda.     

The borel conjecture

We show the Borel Conjecture is consistent with the continuum large.     

Behaviour of the anchoring strength coefficient near a structural transition at a nematic-substrate interface

A nearly symmetric alkoxyphenylbenzoate monomer is found to exhibit a transition from perpendicular to tilted alignment at a lecithin-treated glass substrate several degrees below the nematic-isotropic phase transition. By means of the Freedericksz transition the coefficient B of the anchoring energy has been obtained. It is found that B rapidly decreases, and the tilt susceptibility increases on approaching this transition.     

Forming biocompatible and nonaggregated nanocrystals in water using amphiphilic polymers

High-quality nanocrystals formed in organic solvents can be completely solubilized in water using amphiphilic copolymers containing poly(ethylene glycol) or PEG. These copolymers are generated using a maleic anhydride coupling scheme that permits the coupling of a wide variety of PEG polymers, both unfunctionalized and functionalized, to hydrophobic tails. Thermogravimetric analysis, size exclusion chromatography, cryogenic transmission electron microscopy, and infrared spectroscopy all indicate that the copolymers effectively coat the nanocrystals surfaces. The composite nanocrystal-polymer assemblies can be targeted to recognize cancer cells with Her2 receptor and are biocompatible if their surface coatings contain PEG. In the particular case of semiconductor nanocrystals (e.g., quantum dots), the materials in water have the same optical spectra as well as quantum yield as those formed initially in organic solutions.