RESUMEN
Magnetic domains at the surface of a ferroelectric monodomain BiFeO(3) single crystal have been imaged by hard x-ray magnetic scattering. Magnetic domains up to several hundred microns in size have been observed, corresponding to cycloidal modulations of the magnetization along the wave vector k=(δ,δ,0) and symmetry equivalent directions. The rotation direction of the magnetization in all magnetic domains, determined by diffraction of circularly polarized light, was found to be unique and in agreement with predictions of a combined approach based on a spin-model complemented by relativistic density-functional simulations. Imaging of the surface shows that the largest adjacent domains display a 120° vortex structure.
RESUMEN
Hyperthermia has been shown to have a detrimental effect on experimental and human neoplasms. A water bath immersion system is described to evaluate the effects of systemic hyperthermia (SH) on the growth patterns of the Morris hepatoma 7777 in male Buffalo rats. SH and anesthesia were observed to have no long-term detrimental effects on weight trends or chow consumption. Inhibition of growth was demonstrated for this experimental tumor model at extreme SH (41.5 degree to 42.0 degree C), and it was statistically different (P less than 0.01) from the patterns of tumor growth observed in controls and tumor-burdened animals treated with moderate SH (39..5 degree to 40.0 degree C). Cessation of extreme SH resulted in acceleration of tumor growth so that no difference in tumor volume or animal survival was identified SH resulted in retardation of tumor growth patterns, but its effects were not sustained once treatments were stopped.
