Jianxin Tang Nonmonotonic Temperature Seth

We present two experiments that probe the temperature dependence ofthe flexibility ofthe filamentous virus fd by examining aspects ofthe liquid crystalline nature qf fd suspensions. The first measurement i s of the temperature variation o f the coexisting fd concentrations at the isotropic-cholesteric phase transition. The second measurement is ofthe magneticfield induced birefringence or Cotton-Mouton constant in the isotropic phase as a function of temperature. We compare these measurements with the theoretical treatment of' Onsager, Khokhlov-Semenov, and Chen and conclude thal thejlexibility of fd varies nonmonotonically with temperature und has a minimum in persistence length at 35°C.