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.

Acid–base properties of the active sites responsible for C2+ and CO2 formation over MO–Sm2O3 (M = Zn, Mg, Ca and Sr) mixed oxides in OCM reaction

Abstract: The research investigates the quantitative relationship between the surface basicity of MO–Sm 2 O 3 (M = Zn, Mg, Ca and Sr) mixed oxides and catalytic activity for C 2 + formation. The amount as well as the evolution of surface carbonate species with nature of MO and reaction temperature were analyzed by XRD, TPD, XPS and IR methods to better understand the reaction mechanism. The concentration of surface basic sites responsible for the formation of C 2 + were found to correlate well with the amount of evolved CO 2 in the 300–800 °C temperature range. According to the experimental data, the higher was the catalyst basicity in terms of CO 2 retaining capacity the better was the efficiency for selectively converting methane to C 2 + . The turnover frequency (TOF) values were calculated by measuring the total number basic sites retaining reversible CO 2 in reaction conditions. The experimental results can be explained in a simplified manner by considering a reaction mechanism in which alkaline active sites play a crucial role in methane selective activation to C 2 + whereas the acidic sites, showing little interaction CO 2 , are responsible for methane combustion. A strategy for improving the performances of OCM catalysts is discussed in light of the experimental results.

Isolation method and xeno-free culture conditions influence multipotent differentiation capacity of human Wharton’s jelly-derived mesenchymal stem cells

Abstract: Introduction Human Wharton’s jelly (WJ) has become a preferred source of mesenchymal stem cells (MSCs) whose clinical applications are limited by the use of adequate xeno-free (XF), in vitro manipulation conditions. Therefore, the objective of our study was to characterize WJ-derived MSCs (WJ-MSCs), isolated by different methods and cultured in a commercially available, MSC XF medium, not least of all by investigating their endothelial differentiation capacity.

Proper Motions in Kapteyn Selected Area 103: A Preliminary Orbit for the Virgo Stellar Stream

Abstract: We present absolute proper motions in Kapteyn Selected Area (SA) 103. This field is located 7° west of the center of the Virgo Stellar Stream (VSS), and has a well-defined main sequence representing the stream. In SA 103, we identify one RR Lyrae star as a member of the VSS, according to its metallicity, radial velocity, and distance. VSS candidate turnoff and subgiant stars have proper motions consistent with that of the RR Lyrae star. The three-dimensional velocity data imply an orbit with a pericenter of ~11 kpc and an apocenter of ~90 kpc. Thus, the VSS comprises tidal debris found near the pericenter of a highly destructive orbit. Examining the six globular clusters at distances larger than 50 kpc from the Galactic center, and the proposed orbit of the VSS, we find one tentative association, NGC 2419. We speculate that NGC 2419 is possibly the nucleus of a disrupted system of which the VSS is a part.