RESUMEN
Hybrid organometallic systems offer a wide range of functionalities, including magnetoelectric (ME) interactions. However, the ability to design on-demand ME coupling remains challenging despite a variety of host-guest configurations and ME phases coexistence possibilities. Here, we report the effect of metal-ion substitution on the magnetic and electric properties in the paramagnetic ferroelectric NH2(CH3)2Al1-x Cr x (SO4)2 × 6H2O. Doing so we are able to induce and even tune a sign of the ME interactions, in the paramagnetic ferroelectric (FE) state. Both studied samples with x = 0.065 and x = 0.2 become paramagnetic, contrary to the initial diamagnetic compound. Due to the isomorphous substitution with Cr the ferroelectric phase transition temperature (T c ) increases nonlinearly, with the shift being larger for the 6.5% of Cr. A magnetic field applied along the polar c axis increases ferroelectricity for the x = 0.065 sample and shifts T c to higher values, while inverse effects are observed for x = 0.2. The ME coupling coefficient αME = 1.7 ns/m found for a crystal with Cr content of x = 0.2 is among the highest reported up to now. The observed sign change of αME with a small change in Cr content paves the way for ME coupling engineering.
RESUMEN
A comparative study of fluorescence relaxation kinetics of σ-conjugated poly(methylphenylsilane) (PMPS) polymer film and nanocomposites has been performed by ultrafast time-gated fluorescence measurements at various temperatures. Investigations have revealed a fine structure of excitonic σ-σ* band. We attribute this structure to emission from two spatially independent states with different ordering of the polymer chain segments, type gauche and trans conformations. In contrary to a more ordered polymer poly(di-n-hexylsilane), no clear thermochromic transition has been detected in PMPS film; however, the trans band intensity increases with temperature and with excitation wavelength, but it is absent when polymer is incorporated into nanopores of small diameter.
RESUMEN
The growth of BHK-21 culture cells on the outer surface and in the clear space of capillaries made of phenylone or polyacrylnitrile was studied. The cultivation of cells in the clear space of the capillary extends their survival time and outlines possible ways of continuous cultivation of tissue cells which are cultivated in the attached state.
Asunto(s)
Técnicas Citológicas/instrumentación , Resinas Acrílicas , Animales , Supervivencia Celular , Células Cultivadas , Diseño de Equipo , Estudios de Evaluación como Asunto , Fenilendiaminas , Ácidos Ftálicos , Polímeros , Factores de TiempoRESUMEN
Growth of cell culture BHK-21 in the presence of different fractions of bovine serum has been studied. Growth-promoting activity of the fraction with molecular weight of 100 000 daltons increased with the concentration of this fraction in the medium, but did not reach the activity level of the whole serum. The intensity of cell proliferation similar to that in the presence of the whole serum was achieved due to the combined action of the serum fraction with molecular weight of 100 000 - 200 000 daltons, containing the supposed growth factors and a fraction with low-molecular components of 14 000 daltons. When tested individually, neither of these two fractions showed similar effect.
Asunto(s)
Sustancias de Crecimiento/sangre , Animales , Bovinos , División Celular/efectos de los fármacos , Células Cultivadas , Sustancias de Crecimiento/aislamiento & purificación , Sustancias de Crecimiento/farmacología , Peso Molecular , Factores de TiempoRESUMEN
By cytofluorometry the distribution of cells was studied according to the amount of DNA in a population of BHK-21 cells placed in the media containing a serum fraction that either does not stimulate cell proliferation, or stimulates it until reaching 60% of the limiting density observed in the control. The analysis of cell distribution shown that after the arrest of cell growth cells are accumulated in the G1 phase of the cell cycle to change into the quiescent state. As a control, cytofluorometric analysis of populations of BHK-21 cells cultured under normal conditions in the presence of the 10% whole serum was performed.
Asunto(s)
Proteínas Sanguíneas/farmacología , Células Cultivadas/efectos de los fármacos , Animales , Bovinos , División Celular/efectos de los fármacos , Línea Celular , Cricetinae , ADN/análisis , Riñón , Peso MolecularRESUMEN
The growth of BHK-21 cells exposed to various bovine serum ultrafiltrates has been studied. The intensity of cell multiplication equal to that seen in the presence of the whole serum was provided only by the ultra filtrate containing all components with molecular weights up to 200 000 dalton. Ultrafiltrates containing components with molecular weight up to 70 000 dalton or from 70 000 to 200 000 dalton provided stretching of cells and their partial multiplication. Ultrafiltrates containing components with molecular weight up to 14 000 dalton stimulated only attachment of cells, without stretching.