On the temperature Dependence of the orientational Order Parameter in the Nematic Phase of Cyanophenyl Behzoates

The orientational order parameters fot two liquid crystal materials, 4-cyanophenyl 4-butylbenzoate and 4-cyanophenyl 4-pentylbenzoate, have been derived by measuring the change in the refractive index as function of temperature. The order parameters are compared with MaierSaupe theory, and the sharpness of the transitions has been shown using the Haller's plot.     

Enantioselective synthesis of (+)-gossonorol and related systems using organozinc reagents

The sesquiterpene (+)-gossonorol is prepared in only three synthetic steps in 60% overall yield and 82% ee from commercially available reagents. The key asymmetric step is the catalytic enantioselective addition of dimethylzinc to 5-methyl-1-(2-methylphenyl)hex-4-en-1-one catalyzed by chiral isoborneolsulfonamide ligands in the presence of titanium tetraisopropoxide. The modular approach allows the synthesis not only of the aforementioned natural product but also other products arising from the corresponding processes of ethylation, phenylation, and ethynylation, just by changing the final nucleophilic reagent and using the same isoborneol type ligand.     

Biaxial bulge testing of polymeric sheets

The through thickness total strains of hydrostatically bulged domes of materials are usually determined indirectly. The in-plane circumferential strains are readily measured, and then constancy of volume is invoked to determine the “missing” or unknown strain. Some of our recent work with polymers has shown that volume constancy in large-scale deformation does not hold so that the usual computations of stress and strain during bulging of sheet may be in error. We describe an electrical device that reduces such errors by directly measuring the through thickness (and, thus, the thickness “strain”) for nonmetallic materials.