Hysteresis and ferroelectric liquid crystal displays

One cause of the hysteresis in the voltage-transmittance curve is polarization in the alignment layers brought about by the spontaneous polarization of FLC molecules. The hysteresis was reduced by increasing the conductivity of the alignment layers. The structural changes on switching were examined by measuring time-resolved shifts of FT-IR peaks of selected groups. The shifts of selected groups in the IR peak can be attributed to changes in the local dielectric constants of the ambient environment during switching by molecular orbital calculations. The orientation on switching in the SmC* phase was found to be similar to that in the N* phase.     

Preparation of water-soluble sodium deoxycellulosesulfonate from homogeneously prepared tosylcellulose

Water-soluble sodium deoxycellulosesulfonate (DCS-Na) was prepared by nucleophilic substitution of the p-toluenesulfonyl (tosyl) groups of cellulose p-toluenesulfonate (tosylcellulose) by a sulfonate group in aqueous Na2SO3 solution. In the substitution, the yield and degree of substitution (DS) by the sulfonate group (DSsul) were found to increase with increasing reaction temperature and with reaction time, and reached up to 80% and 0.28, respectively, at 100 °C for 72 h. Although the DS of the tosyl group (DStosyl) decreased with increasing reaction temperature and with reaction time, a respectable amount of tosyl group still remained even at 100 °C for 72 h. Furthermore, the intrinsic viscosity, [], of the DCS-Na obtained decreased considerably with increasing reaction temperature and with reaction time. The decreases in DStosyl and [] were very similar to each other in that increasing DSsul was independent of the reaction temperature and the reaction time. The similarity of the decreases suggests that the mechanisms of scission of the cellulose backbone and the leaving of the tosyl groups (from tosylcellulose) in the nucleophilic substitution were closely related to each other. The partial conversion of the tosyl group in the tosylcellulose to the sulfonate group, by the nucleophilic substitution, was also confirmed by the change in the IR absorption spectrum. The product could be considered to be a ter-polymer from the point of view of the AGU (anhydro glucose unit). Thus, we have AGU-co-DAGUS-Na-tosyl AGU as possible options     

One-Dimensional Heat Conduction with a Class of Automatic Heat-Source Controls

The paper deals with the one-dimensional heat equation withflux boundary conditions and a heat source of the form f(t)K(u(t,x₀)), t>0, where x₀ is a fixed point in the interval (0,1) in which the problem is studied. Thus the heat source isconstant in space for each t and plays the role of an automaticcontroller of the thermal evolution. Existence and uniquenessof solutions are proved under suitable assumptions on the (multivalued)function K and the asymptotic behaviour for t is investigated.     

ChemInform Abstract: Prediction of the Fundamental Vibrational Frequencies for C60 by Local Density Functional Theory

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