Razvan-Ioan Trascu
@anaaslanacademy.ro
Ana Aslan International Foundation
RESEARCH, TEACHING, or OTHER INTERESTS
Family Practice, Geriatrics and Gerontology, General Medicine, Computer Science
Scopus Publications
Scholar Citations
Scholar h-index
Scopus Publications
Luiza Spiru, Răzvan Ioan Traşcu, Ileana Turcu, and Mircea Mărzan
Springer Netherlands
Luiza Spiru, Răzvan Ioan Traşcu, Ileana Turcu, and Mircea Mărzan
Springer Science and Business Media LLC
Mihaela Dumitru Ghelmez, Elena Slavnicu, Cristian Toma, Andreea-Rodica Sterian, and Razvan I. Trascu
SPIE
In this paper, thin films of some fatty acids and fatty acid-cholesterol mixtures were investigated as biological membrane simple models, in order to establish the thermal neutron irradiation influence on these systems, while in the smectic C liquid crystal state. Samples are nonlinear dielectrics with a weak conduction, and nonlinear optical media. They generally present some memore effects. Cholesterol modifies these properties depending on its percentage in mixture and saturated or unsaturated character of the acid. After exposed to a flow of thermal neutrons, texture and behavioral changes, in terms of content of cholesterol in mixtures, and depending on the number of carbon atoms, were emphasized.
Mihaela A. Ghelmez, Bogdan Dumitru, Andreea-Rodica P. Sterian, and Razvan I. Trascu
SPIE
Last years, lasers' applications in medicine and biology were fully enriched by using computer facilities. Our studies were focused on the nonlinear behavior of some substances important for the living matter, as for example fatty acids and their mixtures with cholesterol and some drugs. The experimental data were computer processed and some computer models of the phenomena were built.
Mihaela A. Ghelmez, Elena Slavnicu, and Razvan I. Trascu
SPIE
Sandwich 25micrometers -thick cells with transparent electrodes, filled with some fatty acids (FA) important for the biological membrane (BM), and their mixtures with cholesterol, in the liquid crystal (LC) state, were subjected to a flow of thermal neutrons (4.15 x 1012 neutrons/cm2). Microstructural aspects, electric behaviour and nonlinear optical effects under lower power laser beams were studied before and after irradiation. The laser interaction with FA in the LC state shows the influence of the thermal neutrons irradiation on the electric conduction and the molecular arrangements in the LC systems. Before irradiation, a lens-like effect u nder a He-Ne laser beam has been noticed in the unsaturated (UFA) acids; due to the self-phase modulation effect, a ring pattern appear in far field. The presence of cholesterol (ch) in mixtures modified these effects. After irradiation, the optical nonlinear effects change their feature, increasing in UFA and occurring also in some saturated acids (SFA). These changes are in agreement with the microscopical aspects, the color modifications, and with the electrical state change. The mixture samples are analyzed too. A month after irradiation, SFA seem to slowing return to the initial state, but UFA samples do not come back to the state before irradiation. The nonlinear optical behavior changes dramatically. Ch slightly modifies these changes.