Bulgarian Academy of Sciences

About: Bulgarian Academy of Sciences is a government organization based out in Sofia, Bulgaria. It is known for research contribution in the topics: Coupling constant & Catalysis. The organization has 17989 authors who have published 36276 publications receiving 642820 citations. The organization is also known as: Bulgarian Academy of Sciences，簡稱：BAS & Balgarska Akademiya na Naukite.

Atmospheric temperature measurements using a pure rotational Raman lidar

Abstract: A Raman lidar technique for measuring atmospheric temperature using pure rotational Raman spectra of N2 and O2 is discussed in detail. The use of a double-grating monochromator in the lidar for isolating two portions of the pure rotational Raman spectrum (PRRS) of N2 and O2 and suppressing the line of aerosol light scattering is experimentally shown to be very efficient. The feasibility of the method is convincingly illustrated by the results of laboratory experiments, as well as with measurements of air temperature carried out in the atmosphere. The accuracy of temperature measurements using the ratio of intensities of two portions of PRRS of N2 and O2 was ∼±0.74 K in laboratory experiments. The accuracy of the atmospheric temperature profile measurements using the lidar varied from 0.8 K at altitudes up to 300–400 mto, and slightly exceeded, ±1.5 K at 1-km height. Lidar temperature data are in good agreement with radiosonde data.

Magnetization Reversal by Electric-Field Decoupling of Magnetic and Ferroelectric Domain Walls in Multiferroic-Based Heterostructures

Abstract: We demonstrate that the magnetization of a ferromagnet in contact with an antiferromagnetic multiferroic (${\mathrm{LuMnO}}_{3}$) can be speedily reversed by electric-field pulsing, and the sign of the magnetic exchange bias can switch and recover isothermally. As ${\mathrm{LuMnO}}_{3}$ is not ferroelastic, our data conclusively show that this switching is not mediated by strain effects but is a unique electric-field driven decoupling of the ferroelectric and antiferromagnetic domain walls. Their distinct dynamics are essential for the observed magnetic switching.

Pressure dependence of viscosity of glassforming melts

Abstract: We suggest a model in which the viscosity η is related to the entropy of the system. The model successfully describes the dependence of viscosity on pressure. A master equation is developed that allows a comparison of data obtained at different temperatures. Earlier, in the framework of the same model we described the dependence of viscosity on temperature. The present treatment gives a simple interpretation of T g , the glass transition temperature, which takes places when the disorder in the amorphous system decreases to an extent that the dispersion σ is only 3.5% of maximum value of the activation energy E max .