INFLUENCE OF ULTRASOUND ON THE PERCUTANEOUS-ABSORPTION OF NICOTINATE ESTERS

The influence of ultrasound on the percutaneous absorption of three nicotinate esters was investigated in 10 healthy volunteers in a double-blind placebo controlled crossover clinical trial. Using a specially designed experimental protocol, the effect of continuous output ultrasound (at frequency 3.0 MHz and intensity 1.0 W/cm2 for 5 min) on the percutaneous absorption of methyl, ethyl, and hexyl nicotinates, from gel bases, was investigated. A placebo control, involving massage with each of the gels, without ultrasound for 5 min, was also incorporated. The pharmacodynamic parameter of vasodilation caused by the nicotinates was used to monitor the percutaneous absorption of the drugs. Laser Doppler velocimetry, a noninvasive optical technique, was used to measure vasodilation of the cutaneous vessels within the treatment site. Ultrasound treatment led to enhanced vasodilator response to the nicotinates, therefore indicating an enhancement of their percutaneous absorption. These agents may prove to be useful compounds in examination of the mechanism of action of phonophoresis.

Regular nanodomain vertex arrays in BiFeO3 single crystals

Domain patterns consisting of triangular nanodomains of less than 50 nm size, arranged into long regular vertex arrays separated by stripe domains, were observed by (scanning and high-resolution) transmission electron microscopy and piezoresponse force microscopy in BiFeO3 single crystals grown from solution flux. Piezoresponse force microscopy analysis together with crystallographic analysis by selected area and nanobeam electron diffraction indicate that these patterns consist of ferroelectric 109 degrees domains. A possibility for conserving Kittel's law is discussed in terms of the patterns being confined to the skin layer observed recently on BiFeO3 single crystals.