Stabilization and breakup of optical vortices in presence of hybrid nonlinearity.

We study nonlinear propagation of optical vortices in presence of hybrid nonlinearity as established in a nonconventional biased photorefractive crystal. Our results indicate that under hybrid nonlinearity the breakup of a singly-charged vortex along with the loss of its angular momentum is suppressed considerably as compared with that under conventional self-focusing or self-defocusing nonlinearity. Disintegration of a doubly-charged vortex under hybrid nonlinearity is also presented.

[Experimental research on tea saponin ameliorating nonoxynol spermicidal action in vitro].

Objective: To study the effect of tea saponin in ameliorating nonoxynol(N-9) spermicidal action in vitro.

Methods: According to the improved spermicidal test method in vitro recommended by International Planned Parenthood Foundation (IPPF), we evaluated the minimum spermicidal concentration of N-9, tea saponin and their mixed solution in 20 s and 3 min.

Results: The minimum spermicidal concentration of N-9 in the mixed solution was (0.