Romanian Academy

About: Romanian Academy is a archive organization based out in Bucharest, Romania. It is known for research contribution in the topics: Population & Nonlinear system. The organization has 3662 authors who have published 10491 publications receiving 146447 citations. The organization is also known as: Academia Română & Societatea Literară Română.

Sol-gel iron-doped TiO2 nanopowders with photocatalytic activity

Abstract: The aim of the present work was to establish the influence of the Fe-dopant on the structure and photocatalytic properties of the sol–gel TiO 2 nanopowders The relationship between the synthesis conditions and the properties of titania nanosized materials, such as thermal stability, phase composition, crystallinity, morphology and size of particles was investigated Undoped, 05, 1, 2 and 5 wt% Fe-doped TiO 2 samples have been prepared and structurally characterized by the XRD method Lattice parameters, crystallite sizes, internal strains, as a measure of structural disorder, were determined X-ray photoelectron spectroscopy (XPS) and magnetic measurements completed the structural data study The acceptance of the dopant by the titania lattice was proved by the XRD measurements and the positive values of the magnetic susceptibilities Its addition is responsible for supplementary defects in the crystalline lattice (paramagnetic behaviour) The dopant was present in the low spin state (LS) of Fe 3+ in the sample with 05 wt% iron concentration and in the high spin state (HS) in the other samples It influenced the photocatalytic properties The photocatalytic activity of the prepared nanopowders has been tested in the degradation of nitrobenzene from water, as a first mention in literature The sample with 05 wt% Fe dopant concentration thermally treated at 400 °C presented the best photocatalytic activity

Spectral inverse quantum (Spectral-IQ) method for modeling mesoporous systems: application on silica films by FTIR.

Abstract: The present work advances the inverse quantum (IQ) structural criterion for ordering and characterizing the porosity of the mesosystems based on the recently advanced ratio of the particle-to-wave nature of quantum objects within the extended Heisenberg uncertainty relationship through employing the quantum fluctuation, both for free and observed quantum scattering information, as computed upon spectral identification of the wave-numbers specific to the maximum of absorption intensity record, and to left-, right- and full-width at the half maximum (FWHM) of the concerned bands of a given compound. It furnishes the hierarchy for classifying the mesoporous systems from more particle-related (porous, tight or ionic bindings) to more wave behavior (free or covalent bindings). This so-called spectral inverse quantum (Spectral-IQ) particle-to-wave assignment was illustrated on spectral measurement of FT-IR (bonding) bands’ assignment for samples synthesized within different basic environment and different thermal treatment on mesoporous materials obtained by sol-gel technique with n-dodecyl trimethyl ammonium bromide (DTAB) and cetyltrimethylammonium bromide (CTAB) and of their combination as cosolvents. The results were analyzed in the light of the so-called residual inverse quantum information, accounting for the free binding potency of analyzed samples at drying temperature, and were checked by cross-validation with thermal decomposition techniques by endo-exo thermo correlations at a higher temperature.

Boundary Stabilization of Equilibrium Solutions to Parabolic Equations

Abstract: In this note, a stabilizing feedback boundary controller for the equilibrium solutions to parabolic equations with Dirichlet boundary control is designed. The feedback controller is expressed in terms of the eigenfunctions φj corresponding to unstable eigenvalues {λj}j=1N of the linearized equation. For d=1, this stabilizing procedure is applicable for N=1 only, while for d > 1 it is of conditional nature requiring the independence of ∂φj/∂n on the part of the boundary where the control is applied.

δ Sct-type pulsations in eclipsing binary systems: Y Cam

Abstract: We present the results of a three-continent multisite photometric campaign carried out on the Algol-type eclipsing binary system RZ Cas, in which the primary component has recently been discovered to be a δ Sct-type pulsator. The present observations include, for the first time, complete simultaneous Stromgren uvby light curves together with a few Crawford Hβ data collected around the orbital phase of the first quadrature. The new observations confirm the pulsational behaviour of the primary component. A detailed photometric analysis, based on these observations, is presented for both binarity and pulsation. The results indicate a semidetached system where the secondary fills its Roche lobe. The appearance of the light curves reveals the presence of the mass stream from the secondary component and a hotspot where this stream impacts on the surface of the primary star. There are also some indications of chromospheric activity in the secondary. On the other hand, the pulsational behaviour out-of-primary eclipse can be well described with only one frequency at 64.1935 cd -1 similar to the main peak found by Ohshima et al. The existence of multiperiodicity is not confirmed in our data. Concerning the mode identification, our results indicate non-radial pulsation in a high radial order (n = 6), with l = 2, |m| = 1, 2 as the most suitable. However, additional effects must be taken into account in the predictions. Moreover, the pulsation amplitude in the u band is larger than in b and v, which is unusual among the δ Sct-type variables. This can be explained as due to pulsation in a high n value and close to the blue edge of the δ Sct region. On the other hand, the early data of Ohshima et al. have also been analysed and similar results are found concerning the frequency content and pulsational amplitude. Finally, a revision of all the photometric out-of-primary-eclipse data sets available in the literature is made together with some additional unpublished data leading to interesting findings relative to changes taking place in the pulsation amplitudes and frequencies from season to season. Furthermore, multiperiodicity is probably present in some epochs.